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Question 9: Coordinate-Plane Distance

On this page
  1. Original question and givens
  2. Definition and scope
  3. Step-by-step derivation
  4. Reverse checks
  5. Result
  6. This question review and source binding

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P250-0009 · q-20260912-distance-coordinate-0009

Original question and givens

In the Euclidean plane, P=(-14, 9) and Q=(14, 54). Find the distance d(P,Q).

  • G001 — In the Euclidean plane, P=(-14, 9) and Q=(14, 54). Find the distance d(P,Q).

Definition and scope

Distance uses the nonnegative principal square root, following existing source assumption a3. Coincident points have zero distance; the selected pairs are distinct and have positive distances.

Step-by-step derivation

S001 · implies

Before

P=(-14,9), Q=(14,54)

After

Δx=Q_x−P_x; Δy=Q_y−P_y

Conditions: none

Use the same direction Q−P for both coordinate differences.

Step identifiers and dependencies

Rule: coordinate_difference · Uses: G001

S002 · calculation

Before

Δx := sub(14, -14)

After

Δx = 28

Conditions: none

Subtract -14 from 14; keep parentheses around negative coordinates.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S001

S003 · calculation

Before

Δy := sub(54, 9)

After

Δy = 45

Conditions: none

The vertical difference is 54 minus 9.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

(Δx)² := square(28)

After

(Δx)² = 784

Conditions: none

Square the entire horizontal difference, not just the subtracted coordinate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

(Δy)² := square(45)

After

(Δy)² = 2025

Conditions: none

The square is nonnegative even when the vertical difference is negative.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

d² := sum(784, 2025)

After

d² = 2809

Conditions: none

Add the two squares in the Euclidean distance formula.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · implies

Before

d²=2809, d≥0

After

d=√(2809)=53

Conditions: d≥0

Since 53²=2809 and distance is nonnegative, choose the nonnegative root 53.

Step identifiers and dependencies

Rule: nonnegative_square_root · Uses: G001, S006

S008 · calculation

Before

answer² := square(53)

After

answer² = 2809

Conditions: none

Square the proposed distance to recover the original sum of squares.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S007

Reverse checks

  • S008 · premise_and_result_audit — Recompute answer² with exact rational arithmetic, not rounded decimals.
  • S007 · premise_and_result_audit — The negative root is not a distance, and squared distance is not distance itself.
  • S006 · premise_and_result_audit — Recompute d² with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute (Δy)² with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute (Δx)² with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute Δy with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Recompute Δx with exact rational arithmetic, not rounded decimals.
  • S001 · premise_and_result_audit — Swapping the points changes both signs but not the sum of squares.

Result

53

The distance is 53.

This question review and source binding

Review date: 2026-10-24

Original questions, answers, step expressions, numeric ASTs and historical records are retained. Source candidate labels remain historical and are not overwritten as formal proof.

Source hashes and review receipts
  • input commit: 0f7be61e2c22317a4075561dc822c87d881a50db
  • original question SHA-256: 8ea4566fbc7d7d274848c598447394a1d4fe7ccb6ab22b82d5c186e474648a26
  • candidate record SHA-256: da9f128116951017b24f10f743bd2738d0c85d4cc8889dc2fb18b642cabb1337
  • semantic review receipt SHA-256: ada91cd601dc368efd790cdd3aa80d0c7432d82b465fcdd1eef5148d3959755c
  • question-first witness SHA-256: c36a153d3b48c84ba1bb7f6534cc6b835c243b74dd8080300b8026ab133fc6f6
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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