GELE Adjustment Computations (Least Squares) — Condition Equations and Figure AdjustmentMemory Anchors
If you keep missing Condition Equations and Figure Adjustment items on your GELE mocks despite having read the notes, the gap is usually recall speed. Memory anchors close that gap. These Condition Equations and Figure Adjustment mnemonics have been tuned to the kinds of triggers Professional Regulation Commission (PRC) — Board of Geodetic Engineering builds into GELE Adjustment Computations (Least Squares) questions.
Exam context
Professional Regulation Commission (PRC) — Board of Geodetic Engineering runs the Geodetic Engineer Licensure Examination on September 2026. Its Adjustment Computations (Least Squares) section sits under a "Core" weighting, and Condition Equations and Figure Adjustment is the 3rd chapter in the 5-chapter GELE Adjustment Computations (Least Squares) rotation. The GELE passing mark is 70% weighted average, no sub-test below 50%, and the most recent 2026 paper drew about a meaningful share of questions from Adjustment Computations (Least Squares).
Condition Equations and Figure Adjustment - Memory Anchors
Memory techniques transform abstract geodetic formulas into vivid mental images that stick for life. Research shows that attaching emotion, story, and spatial association to information increases recall by up to 600% compared to rote reading. For the PRC Geodetic Engineer board exam, where you must recall correction signs, spherical excess conditions, and weighted distribution rules under time pressure, these anchors act as instant mental shortcuts. Instead of re-deriving formulas during the exam, you simply fire the anchor — the answer appears automatically. Use these mnemonics, analogies, stories, and visual chains to convert every key concept in Condition Equations and Figure Adjustment into a permanent memory trace.
Anchors
Tags
- definition
- concept
- analogy
Topic
Condition Equations — Definition
Concept
What a condition equation does — it enforces exact geometric truth
Anchor Id
A1
Difficulty
easy
Memory Aid
Imagine a strict barangay captain (the condition equation) who insists that all the land areas within his barangay MUST add up to exactly the recorded total land area of the barangay. If the surveyors' measurements add up to slightly more or less, the captain forces them to re-distribute the excess or deficit among all owners until the total is exactly right. The condition equation is that barangay captain — uncompromising, always demanding the geometrically exact total.
Anchor Type
analogy
Why It Works
Filipino students relate strongly to authority figures enforcing rules. The barangay captain analogy maps perfectly: the 'law' is the geometric condition, the 'excess land' is the misclosure, and the 're-distribution' is the correction applied to each observation.
Example Usage
When asked 'What does a condition equation enforce?' — think of the barangay captain demanding the exact total, then write: a condition equation states the geometric relationship that adjusted observations must satisfy exactly.
Recall Trigger
Picture a stern barangay captain holding a ruler and a calculator.
Tags
- formula
- definition
- mnemonic
Topic
Misclosure Formula
Concept
Misclosure = observed sum minus required total
Anchor Id
A2
Difficulty
easy
Memory Aid
Remember 'O-R = MisC' — Observed minus Required equals Misclosure. Say it as: 'OR MisC' — like saying 'OR MISC(hief)' — the mischievous difference between what you measured and what geometry demands!
Anchor Type
mnemonic
Why It Works
The word 'mischief' (MISC) is phonetically close to 'misclosure' and carries a negative connotation — measurements being naughty and not obeying geometry — making the formula memorable.
Example Usage
Board problem: 'Angles of a triangle sum to 180°00′12″. Find the misclosure.' — trigger 'OR MisC': Observed (180°00′12″) minus Required (180°00′00″) = +12″ misclosure.
Recall Trigger
Think of a mischievous kid (MISC-hief) causing trouble by giving you the wrong total.
Tags
- formula
- rhyme
- sequence
Topic
Equal-Weight Correction Formula
Concept
Correction per angle (equal weights) = −misclosure / n
Anchor Id
A3
Difficulty
easy
Memory Aid
Chant this board-exam rhyme: 'Misclosure you divide, then flip the sign, that's your ride — each angle gets a piece, negative to find peace!' The flip (negation) ensures the corrected sum reaches exactly the required total.
Anchor Type
rhyme
Why It Works
Rhymes engage the phonological loop of working memory, creating an auditory chain that is automatically replayed when the concept is triggered.
Example Usage
Triangle misclosure = +12″, n = 3. Rhyme: 'divide +12 by 3 = +4, flip sign = −4″ per angle.' Each adjusted angle = measured angle − 4″.
Recall Trigger
Hum the rhyme silently whenever you see 'adjust equally' in a problem.
Tags
- sign convention
- analogy
- common mistake
Topic
Sign Convention for Corrections
Concept
Correction sign is always OPPOSITE to the misclosure sign
Anchor Id
A4
Difficulty
easy
Memory Aid
Think of a seesaw (tiimbangan). If one side goes UP (positive misclosure), you must push it DOWN (negative correction) to level it. The correction always opposes the misclosure — just like a seesaw always moves opposite to the heavier side.
Anchor Type
analogy
Why It Works
The seesaw is a universal physical intuition for balance and opposition. Visualizing the leveling action directly encodes the sign-flip rule.
Example Usage
Misclosure = −9″ (angles summed too little). Correction = +3″ per angle (we push the sum up). Trigger: seesaw goes down on the left → push right side down → correction is +.
Recall Trigger
Picture a seesaw. Whichever side the misclosure lifts, the correction pushes down.
Tags
- definition
- formula
- acronym
Topic
Triangle Angle Condition
Concept
Triangle angle condition — plane: sum must equal exactly 180°
Anchor Id
A5
Difficulty
easy
Memory Aid
Use the acronym P-180: 'P for Plane, 180 for the target.' Plane Triangle → 180°. Repeat: 'P-180, P-180, Plane is 180.'
Anchor Type
acronym
Why It Works
Simple paired acronyms are among the fastest retrieval cues. The letter P visually resembles an angle symbol, reinforcing the association.
Example Usage
Board question: 'What is the required sum of angles in a plane triangle?' Trigger P-180 → answer: 180°00′00″.
Recall Trigger
See the letter P → Plane → 180°.
Tags
- formula
- concept
- spherical excess
- micro_story
Topic
Spherical Excess and Triangle Condition
Concept
Spherical triangle condition — sum must equal 180° + spherical excess ε
Anchor Id
A6
Difficulty
medium
Memory Aid
Story: Engineer Marites is adjusting a first-order triangulation network covering Luzon. She notices her triangle spans over 100 km — so large that the Earth's curvature gives the triangle an 'extra allowance' called spherical excess ε. She tells her crew: 'Normal triangles get 180°, but OUR big triangle gets a BONUS — 180° plus ε!' The bonus ε is the Earth saying: 'You're big enough to notice my roundness, so I'll give you extra degrees.'
Anchor Type
micro_story
Why It Works
A relatable Filipino engineer character (Marites) and the concept of a 'bonus' make the extra ε memorable. The narrative context (large Philippine triangulation network) grounds the concept in professional practice.
Example Usage
Spherical triangle, ε = 5″. Required sum = 180°00′05″. Observed sum = 180°00′17″. Misclosure = +12″. Each angle corrected by −4″.
Recall Trigger
Think of Engineer Marites and her 'bonus degrees' for large triangles.
Tags
- definition
- visual_association
- sequence
Topic
Horizon Condition
Concept
Horizon (station) condition — all angles around a point must sum to 360°
Anchor Id
A7
Difficulty
easy
Memory Aid
Visualize a FULL PIZZA. A whole pizza is a full circle = 360°. When you observe all the angles around a surveying station, you are slicing that pizza. No matter how many slices, the total must be the full pizza (360°). If the slices add up to 360°06″, you have an extra 6″ of imaginary pizza — trim it away equally.
Anchor Type
visual_association
Why It Works
The pizza circle is an extremely intuitive visual for 360°. Filipino students enjoy food analogies, which activate emotional memory pathways.
Example Usage
Three angles at station B: 120°00′06″ + 119°59′54″ + 120°00′06″ = 360°00′06″. Pizza has 6″ extra. Trim 2″ per slice. Adjusted angles: 120°00′04″, 119°59′52″, 120°00′04″.
Recall Trigger
Picture a full round pizza every time you see 'horizon condition' or 'angles at a station.'
Tags
- concept
- analogy
- loop closure
Topic
Loop Closure Condition
Concept
Loop (level/traverse) closure condition — misclosure must return to zero
Anchor Id
A8
Difficulty
medium
Memory Aid
Imagine a jeepney route. It leaves the terminal (starting BM), travels all the roads (observations), and MUST return to the exact same terminal (closing BM). If the odometer reads 2 cm more than the road length should give, that is your 2 cm misclosure — you distribute it along the route proportionally to each road segment's length.
Anchor Type
analogy
Why It Works
The jeepney route is intimately familiar to Filipino students. The return-to-terminal concept directly models loop closure. The odometer surplus = misclosure.
Example Usage
Level loop misclosure = +12 mm over 4 equal legs. Correction per leg = −3 mm. Each elevation difference is reduced by 3 mm.
Recall Trigger
Picture a jeepney returning to its terminal. Misclosure = the extra distance on the odometer.
Tags
- weighted correction
- analogy
- formula
- process
Topic
Weighted Distribution
Concept
Weighted distribution — weaker observations get MORE correction
Anchor Id
A9
Difficulty
hard
Memory Aid
Think of dividing chores in a household. The family member who is LESS reliable (weaker) gets ASSIGNED MORE of the unfinished work (misclosure) to compensate. The more uncertain your measurement, the bigger your correction — because the adjustment trusts you less.
Anchor Type
analogy
Why It Works
Household chore division is a universal Filipino family experience. The 'unreliable member gets more work' maps directly onto the weighted correction principle.
Example Usage
Triangle misclosure = +9″. Angle 1 variance = σ², Angle 2 variance = σ², Angle 3 variance = 2σ² (twice as uncertain). Angle 3 receives more of the −9″ correction (split: −2.25″, −2.25″, −4.5″).
Recall Trigger
The least reliable family member gets the most chores. The weakest observation gets the most correction.
Tags
- formula
- definition
- mnemonic
Topic
Number of Condition Equations
Concept
Number of conditions (r) in a figure = observed quantities minus minimum needed
Anchor Id
A10
Difficulty
hard
Memory Aid
Remember 'r = O − N': 'r is the REDUNDANCY, O is OBSERVED angles, N is the NECESSARY minimum.' Chant: 'Redundancy = Observed minus Necessary.' Or visualize: 'r = O − N' → 'RON' — imagine your classmate RON who always does MORE work than the minimum (he's redundant in the best way).
Anchor Type
mnemonic
Why It Works
Using a person's name (RON) as a phonetic hook for the formula r = O − N creates a personal, emotionally tagged memory link.
Example Usage
A braced quadrilateral has 8 observed angles; minimum needed = 5. r = 8 − 5 = 3 condition equations to write.
Recall Trigger
Think of classmate RON (Redundancy = Observed − Necessary).
Tags
- definition
- process
- verification
Topic
Exact Satisfaction of Conditions
Concept
The adjusted observations must satisfy the condition EXACTLY
Anchor Id
A11
Difficulty
easy
Memory Aid
Story: Engr. Bantay is reviewing a triangulation report. He checks the adjusted angles of every triangle. He does not accept '180°00′01″' — it must be EXACTLY 180°00′00″. He says, 'Hindi ako tumatanggap ng halos-tama (I do not accept almost-correct). Exact lang!' That is the rule of condition equations — the residual after adjustment must be exactly zero.
Anchor Type
micro_story
Why It Works
The strict Filipino professional authority figure (Engr. Bantay means 'guard/watcher') makes the 'exact satisfaction' rule memorable through a relatable authority scenario.
Example Usage
After distributing corrections, always verify: sum of adjusted angles = 180°00′00″ (or 180° + ε for spherical). If not, re-check your arithmetic.
Recall Trigger
Hear Engr. Bantay say 'Exact lang!' every time you check adjusted observations.
Tags
- sign convention
- rhyme
- formula
Topic
Sign Convention
Concept
Correction is negative when misclosure is positive (and vice versa)
Anchor Id
A12
Difficulty
easy
Memory Aid
Rhyme: 'Positive misclosure, negative fix — that is how the surveyor mixes! Negative misclosure, positive cure — keep those signs straight and you'll be sure!'
Anchor Type
rhyme
Why It Works
The opposing rhythm of the rhyme mirrors the mathematical opposition, embedding the sign rule through dual phonological repetition.
Example Usage
Misclosure = +12″ → correction = −4″ per angle. Misclosure = −9″ → correction = +3″ per angle. Rhyme confirms the sign flip.
Recall Trigger
Sing the rhyme mentally when you compute a correction.
Tags
- visual_association
- formula
- horizon condition
Topic
Horizon Condition with n=4
Concept
Four-angle horizon condition (n=4 angles around a point)
Anchor Id
A13
Difficulty
easy
Memory Aid
Visualize a COMPASS ROSE with 4 petals (N, E, S, W), each petal an angle. The 4 petals must perfectly fill the 360° circle. If one petal is slightly too big, all four must shrink by misclosure/4. The compass rose always completes the full circle.
Anchor Type
visual_association
Why It Works
The compass rose is a professional symbol geodetic engineers see constantly. Its four-fold symmetry visually encodes the n=4 equal distribution.
Example Usage
Four angles at a station sum to 360°00′08″. Misclosure = +8″. Correction = −2″ per angle. Compass rose trims each petal by 2″.
Recall Trigger
Picture a 4-petal compass rose on your total station when you see 4 horizontal angles at a station.
Tags
- definition
- formula
- mnemonic
- spherical excess
Topic
Spherical Excess
Concept
Spherical excess ε — the 'bonus' angle caused by Earth's curvature
Anchor Id
A14
Difficulty
medium
Memory Aid
Remember: ε is the 'Earth Extra.' The Greek letter ε looks like a curve — just like the Earth's surface. Big triangles on the curved Earth get an EXTRA amount ε added to the flat 180°. Formula: Required = 180° + ε. Chant: 'Earth Extra makes 180 better.'
Anchor Type
mnemonic
Why It Works
The visual similarity between ε and a curved surface directly encodes the concept of curvature. The alliterative phrase 'Earth Extra' creates a fast retrieval cue.
Example Usage
ε = 8″ for a large triangle. Required sum = 180°00′08″. Observed = 180°00′26″. Misclosure = +18″. Correction = −6″ per angle.
Recall Trigger
See ε → 'Earth Extra' → add to 180°.
Tags
- sequence
- process
- acronym
Topic
Adjustment Workflow
Concept
The adjustment workflow: observe → compute misclosure → compute correction → apply → verify
Anchor Id
A15
Difficulty
easy
Memory Aid
Use the acronym 'OCCAV': Observe, Compute misclosure, Compute Correction, Apply correction, Verify. Pronounce it 'OH-KAV' — like saying 'O, kaya!' (Oh, I can do it!) in Filipino — a confident declaration that you can complete the adjustment.
Anchor Type
acronym
Why It Works
The Filipino phrase 'O, kaya!' (Of course I can!) is a motivational tag that links the adjustment procedure to a positive emotional state, embedding the 5-step sequence.
Example Usage
On the board exam: see a figure adjustment problem → whisper 'O, kaya!' → write OCCAV steps → solve systematically.
Recall Trigger
Say 'O, kaya!' before every figure adjustment problem. Then list: Observe, Compute misclosure, Compute Correction, Apply, Verify.
Tags
- weighted correction
- micro_story
- formula
- process
Topic
Weighted Correction Distribution
Concept
Unequal weights — correction proportional to variance (weaker = more correction)
Anchor Id
A16
Difficulty
hard
Memory Aid
Story: Three barangay tanods (watchmen) are each assigned to guard a boundary. Tanod A and B are experienced (low variance σ²). Tanod C is new and unreliable (variance 2σ²). When the team makes a mistake that needs to be fixed, the supervisor assigns MORE corrective tasks to Tanod C because 'you are least certain, so you carry more of the adjustment.' Moral: Higher variance = lower weight = MORE correction assigned.
Anchor Type
micro_story
Why It Works
The tanod hierarchy is culturally familiar. The assignment of extra work to the least reliable member maps perfectly onto weighted adjustment logic.
Example Usage
Weights: w₁=1, w₂=1, w₃=0.5 (Tanod C, half weight). Corrections inversely proportional to weights: c₃ is larger than c₁ or c₂.
Recall Trigger
Picture the inexperienced tanod carrying a heavier sack of corrections.
Tags
- verification
- process
- visual_association
Topic
Verification of Adjusted Observations
Concept
Verification check — adjusted angles must sum to EXACTLY the required total
Anchor Id
A17
Difficulty
easy
Memory Aid
Imagine a DIGITAL SCOREBOARD at the end of a basketball game that must show exactly 48:00 (full game time). If the clock shows 48:03, the timekeeper made an error — the adjustment is wrong. After applying corrections, your angle sum is the scoreboard — it MUST read the exact required total. Any deviation means you re-check.
Anchor Type
visual_association
Why It Works
Filipinos are passionate about basketball. The scoreboard finality (game over = exact time) creates a strong emotional hook for the verification rule.
Example Usage
After adjusting triangle angles, compute: 60°00′06″ + 59°59′58″ + 59°59′56″ = 180°00′00″. Scoreboard reads perfect — adjustment verified!
Recall Trigger
See the buzzer go off — your scoreboard (adjusted sum) must show EXACTLY the required total.
Tags
- analogy
- formula
- loop closure
- weighted correction
Topic
Proportional Correction for Level Loops
Concept
Loop level misclosure distributed proportional to distance
Anchor Id
A18
Difficulty
medium
Memory Aid
Imagine spreading fertilizer (pataba) along a farm road. Longer sections of road get MORE fertilizer because they cover more ground. Similarly, longer level sections carry more potential for error, so they receive a larger share of the misclosure correction. Short sections get less, long sections get more — just like fertilizing proportionally.
Anchor Type
analogy
Why It Works
Farming and proportional distribution are deeply familiar to many Filipino students. The fertilizer analogy converts an abstract weighting rule into a visual, tactile memory.
Example Usage
Level loop: section lengths 2 km, 3 km, 5 km (total 10 km). Misclosure = −30 mm. Corrections: +6, +9, +15 mm (proportional to length).
Recall Trigger
Visualize a farmer spreading fertilizer unevenly — more on long sections, less on short ones.
Tags
- common mistake
- micro_story
- spherical excess
Topic
Spherical Excess Pitfall
Concept
Common pitfall — forgetting to add ε in the spherical triangle condition
Anchor Id
A19
Difficulty
medium
Memory Aid
Story: Reviewee Dodong forgot to add ε = 5″ to his target sum. He computed misclosure = +17″ and got corrections of −5.67″ each. His board answer was WRONG. The examiner's comment: 'Hindi maliit ang Pilipinas para kalimutan ang spherical excess.' (The Philippines is not small enough to forget spherical excess.) Dodong's mistake cost him 2 points. Remember Dodong — never forget ε!
Anchor Type
micro_story
Why It Works
Failure stories with named Filipino characters create vivid cautionary memory traces. Naming the mistake 'Dodong's Error' gives it a memorable label.
Example Usage
Before computing misclosure for a first-order triangle, ALWAYS check: is ε given? If yes, target = 180° + ε. Don't be Dodong.
Recall Trigger
Think of Dodong's 2-point mistake whenever you see a large triangle problem.
Tags
- concept
- analogy
- least squares
- definition
Topic
Condition Equations and Least Squares
Concept
Figure adjustment is a direct application of the condition-equation least-squares concept
Anchor Id
A20
Difficulty
hard
Memory Aid
Think of condition equations as the CONSTITUTION of measurements — the supreme law that adjusted values must obey. Least squares is the IMPLEMENTING RULES (IRR) — the method that distributes corrections fairly. Just as Philippine laws (like PD 1529 on land registration) set requirements and the implementing rules define how to meet them, condition equations set the geometric law and least squares defines HOW to satisfy it optimally.
Anchor Type
analogy
Why It Works
Connecting geodetic theory to the Philippine legal system (PD 1529, RA 8560) makes the abstract theory professionally grounded and culturally resonant.
Example Usage
When explaining figure adjustment: 'The triangle angle condition (180°) is the law; equal distribution of the 12″ misclosure is the least-squares-optimal implementation of that law.'
Recall Trigger
Condition equation = Constitution (the law). Least squares = IRR (how to obey the law).
Revision Game
Misclosure
Clue
I am the difference between what you measured and what geometry demands. If triangle angles sum to 180°00′12″, I am +12″. What am I?
Memory Link
A2 — OR MisC mnemonic (Observed minus Required = Misclosure)
Correction (cᵢ)
Clue
I am the rule that says: positive misclosure → negative me; negative misclosure → positive me. I am always opposite in sign. What am I?
Memory Link
A4 — The seesaw analogy; A12 — the correction sign rhyme
Spherical excess (ε)
Clue
I am the 'bonus degrees' that large spherical triangles get because Earth is round. I am added to 180° to find the target sum. What am I?
Memory Link
A14 — Earth Extra ε mnemonic; A6 — Engineer Marites' bonus story
Horizon (station) condition
Clue
I am a full pizza. Every slice (angle) at a station must fill me completely. My exact value is 360°. What condition am I?
Memory Link
A7 — Pizza visual association for 360° at a station
OCCAV
Clue
I am the 5-step Filipino battle cry of figure adjustment. Say 'O, KAYA!' and I unlock: Observe, Compute misclosure, Compute Correction, Apply, Verify. What acronym am I?
Memory Link
A15 — OCCAV acronym and 'O, kaya!' trigger
Weighted correction distribution (correction proportional to variance)
Clue
I am the principle that says the WEAKEST observation carries the BIGGEST correction — like the newest tanod being assigned the most corrective duties. What distribution rule am I?
Memory Link
A9 — Household chore analogy; A16 — Barangay tanod micro-story
Spherical excess ε (forgetting to include ε in the target sum)
Clue
I am Dodong's costly mistake on the board exam: he forgot to add me to 180° when computing the required sum for a large triangle. He lost 2 points. What am I?
Memory Link
A19 — Dodong's cautionary micro-story about the spherical excess pitfall
Verification (checking that adjusted sum equals required total exactly)
Clue
I am the final scoreboard check at the buzzer of a basketball game. After applying all corrections, I must read EXACTLY the required total — 180°, 360°, or 180°+ε. Miss me and your adjustment is wrong. What step am I?
Memory Link
A17 — Basketball scoreboard visual association; A11 — Engr. Bantay 'Exact lang!' story
Formula Mnemonics
Formula
Misclosure = Σ(observed) − required total
Mnemonic
OR MisC — Observed minus Required = Misclosure. 'OR MISC-hief': measurements being mischievous by not obeying geometry.
When To Use
First step in ANY figure adjustment problem. Always compute misclosure before finding corrections.
What Each Part Means
Σ(observed) = arithmetic sum of all raw measured angles/quantities; required total = geometrically exact value (180°, 360°, 180°+ε, etc.); misclosure = the violation of the condition.
Formula
cᵢ = −misclosure / n (equal weights)
Mnemonic
FLIP and DIVIDE: Divide the misclosure by n, then FLIP the sign. 'Positive misclosure, negative fix.' The correction opposes the misclosure.
When To Use
When all observations are of equal precision/weight. Standard case for most board exam triangle and horizon problems.
What Each Part Means
cᵢ = correction applied to each observation; misclosure = computed violation; n = total number of observations being adjusted equally; negative sign = correction opposes misclosure direction.
Formula
Required sum (spherical triangle) = 180° + ε
Mnemonic
Earth Extra ε: ε is the 'Earth Extra' added to 180° for large triangles. ε looks like a curve — like Earth's curved surface. Never forget the bonus.
When To Use
For geodetic (first-order) triangulation covering large areas where Earth's curvature is not negligible. A value of ε will always be given in board problems.
What Each Part Means
180° = flat-triangle angle sum; ε = spherical excess (computed from the triangle area and Earth's radius); the sum '180° + ε' is the target the adjusted angles must reach.
Formula
Required sum (horizon condition) = 360°
Mnemonic
Full PIZZA = 360°. All slices (angles at a station) must fill the whole pizza.
When To Use
When multiple horizontal angles are measured at a single station completing a full 360° sweep.
What Each Part Means
All horizontal angles measured around a station in a full revolution must sum to exactly 360°00′00″. This is the station/horizon condition.
Formula
Weighted correction: cᵢ ∝ σᵢ² (proportional to variance, inversely to weight)
Mnemonic
HEAVY DOUBT, HEAVY FIX: The observation with the HIGHEST variance (most doubt) gets the BIGGEST fix (correction). High σ² = Heavy correction.
When To Use
When observations have unequal precision — different instruments, different conditions, or explicitly different weights given in the problem.
What Each Part Means
cᵢ = individual correction; σᵢ² = variance of observation i; higher variance → lower weight wᵢ = 1/σᵢ² → larger share of misclosure assigned to that observation.
Formula
Verification: Σ(adjusted) = required total (residual = 0)
Mnemonic
SCOREBOARD CHECK: After applying all corrections, sum the adjusted values. The scoreboard must show EXACTLY the required total. Any deviation = arithmetic error.
When To Use
ALWAYS as the final step of every figure adjustment. Non-negotiable verification.
What Each Part Means
Each adjusted observation = raw observation + correction; their sum must equal the geometric requirement exactly (180°, 360°, 180°+ε). This confirms the adjustment is internally consistent.
Quick Recall Chains
Chain Title
Steps of Figure Adjustment (OCCAV Chain)
Recall Test
Without looking, list the 5 steps of figure adjustment in order. Can you spell OCCAV and define each letter?
Memory Chain
Say 'O, KAYA!' (Filipino: 'Oh, I can!'). Each letter links: O=Observe, K≈C=Compute misclosure, A≈C=Compute Correction, Y=applY, A=vAlidAte. Complete the chain: 'O → compute MISCLOSURE → compute CORRECTION → APPLY → VERIFY = O,KAYA!'
Items To Remember
- Observe — record the raw measured angles
- Compute misclosure — apply formula: Σ(observed) − required
- Compute correction — cᵢ = −misclosure / n
- Apply correction — add cᵢ to each raw angle
- Verify — check that adjusted sum equals required total
Chain Title
Types of Condition Equations
Recall Test
Name 4 types of condition equations and their required totals. What is the target sum for a spherical triangle with ε = 10″?
Memory Chain
Story chain: 'A PLANE TRIANGLE (180°) grew so big it became SPHERICAL (+ε), then looked all around a STATION (360°), traveled a LOOP (closure = 0), and finally measured every SIDE (log-sine condition).' Each bold word triggers one condition type.
Items To Remember
- Triangle angle condition: sum = 180° (plane)
- Spherical triangle condition: sum = 180° + ε
- Horizon (station) condition: sum = 360°
- Loop/traverse closure condition: misclosure = 0
- Side condition (log-sine equation) in triangulation networks
Chain Title
Common Board Pitfalls to Avoid
Recall Test
What 5 mistakes does FUSAV warn you against? Recite them without looking.
Memory Chain
Acronym FUSAV: Flip sign, Use 180°+ε for spherical, Separate equal from weighted, Always verify, Verify n. Chant 'FUSAV saves marks!' before starting any adjustment problem.
Items To Remember
- Forgetting to flip the sign (correction = NEGATIVE of misclosure per angle)
- Using 180° as target for a spherical triangle (must add ε)
- Applying equal corrections when weights are unequal
- Skipping the verification step
- Using wrong n (number of adjusted observations)
Chain Title
Correction Sign Rule
Recall Test
If misclosure = −15″ and n = 5, what is the correction per angle? (Answer: +3″)
Memory Chain
Seesaw image: Misclosure goes UP (+) → correction pushes DOWN (−). Misclosure goes DOWN (−) → correction pushes UP (+). Always OPPOSITE. Divide by n for magnitude. Add to each angle. Check the balance.
Items To Remember
- Positive misclosure → Negative correction per angle
- Negative misclosure → Positive correction per angle
- Magnitude = |misclosure| / n
- Apply correction by algebraically adding to raw observation
- Verify: corrected sum = required total
Previous chapter
Least Squares — Observation Equations
Next chapter
Adjustment of Level Nets and Traverses
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