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Question 6576: Labeled Opposite Endpoints and Squared Side

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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← Question derivation index · Original question batch

R0012-06576 · q-20261009-advance-20261013-r07-triangle-0026

Original question and givens

In one equal-unit orthogonal Euclidean frame, labeled A,B,C have indices 1,2,3 and points=[[0, 1], [0, 0], [1, 0]]. The triangle is qualified as distinct and noncollinear, vertex=1. Give (other two vertex indices, opposite side’s squared L2 distance), not its distance.

  • G001 — In one equal-unit orthogonal Euclidean frame, labeled A,B,C have indices 1,2,3 and points=[[0, 1], [0, 0], [1, 0]]. The triangle is qualified as distinct and noncollinear, vertex=1. Give (other two vertex indices, opposite side’s squared L2 distance), not its distance.

Definition and scope

Use the original question domain, assumptions and cited MKO definitions. This item has second-context mathematical and bilingual review, with the model, answer and every arithmetic step independently recomputed from the original parameters; the source question remains a candidate.

Step-by-step derivation

S001 · implies

Before

[[0, 1], [0, 0], [1, 0]]

After

original vertex labels1,2,3 in an equal-unit orthogonal Euclidean frame

Conditions: none

Retain the original A,B,C order;the squared-coordinate formula uses equal units and orthogonal axes.Do not read values from a sketch or assume candidate vertices already form a triangle.

Step identifiers and dependencies

Rule: labelled_triangle_coordinate_scope · Uses: G001

S002 · implies

Before

[[0, 1], [0, 0], [1, 0]]

After

three distinct points=Yes

Conditions: none

Check distinctness separately from noncollinearity;collinear points may be distinct,while repeated vertices do not form a proper triangle.

Step identifiers and dependencies

Rule: distinct_triangle_vertex_check · Uses: G001, S001

S003 · calculation

Before

ABC first vector component0 := sub(0, 0)

After

ABC first vector component0 = 0

Conditions: none

The first edge vector is the second vertex minus the first.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

ABC first vector component1 := sub(0, 1)

After

ABC first vector component1 = -1

Conditions: none

The first edge vector is the second vertex minus the first.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

ABC second vector component0 := sub(1, 0)

After

ABC second vector component0 = 1

Conditions: none

The second edge vector is the third vertex minus that same first vertex.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

ABC second vector component1 := sub(0, 1)

After

ABC second vector component1 = -1

Conditions: none

The second edge vector is the third vertex minus that same first vertex.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · calculation

Before

ABC cross positive term := mul(0, -1)

After

ABC cross positive term = 0

Conditions: none

Compute u_x v_y first.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S006

S008 · calculation

Before

ABC cross negative term := mul(-1, 1)

After

ABC cross negative term = -1

Conditions: none

Compute u_y v_x separately,retaining subtraction for the next step.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S007

S009 · calculation

Before

ABC signed determinant := sub(0, -1)

After

ABC signed determinant = 1

Conditions: none

Subtract to obtain signed double area;do not erase label orientation with an absolute value.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S008

S010 · implies

Before

distinct=Yes;signed determinant=1

After

proper triangle=Yes

Conditions: none

A proper triangle needs distinct vertices and nonzero determinant;this judges the supplied coordinates,not a general geometric construction proof.

Step identifiers and dependencies

Rule: triangle_nondegenerate_coordinate_qualification · Uses: G001, S009

S011 · implies

Before

marked vertex=1

After

opposite endpoints=[2, 3]

Conditions: none

The opposite-side endpoints are the other two original labels,not a reordered coordinate or side-length list.

Step identifiers and dependencies

Rule: original_label_opposite_side · Uses: G001, S010

S012 · calculation

Before

opposite side coordinate difference0 := sub(0, 1)

After

opposite side coordinate difference0 = -1

Conditions: none

Subtract matching coordinates,allowing rational midpoint coordinates.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S011

S013 · calculation

Before

opposite side difference squared0 := square(-1)

After

opposite side difference squared0 = 1

Conditions: none

Square each difference;its sign does not affect squared length.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S012

S014 · calculation

Before

opposite side coordinate difference1 := sub(0, 0)

After

opposite side coordinate difference1 = 0

Conditions: none

Subtract matching coordinates,allowing rational midpoint coordinates.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S013

S015 · calculation

Before

opposite side difference squared1 := square(0)

After

opposite side difference squared1 = 0

Conditions: none

Square each difference;its sign does not affect squared length.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S014

S016 · calculation

Before

opposite side squared distance := sum(1, 0)

After

opposite side squared distance = 1

Conditions: none

Add the two squares in the equal-unit orthogonal L2 frame.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S015

S017 · implies

Before

([2, 3], 1)

After

second field is squared length,not length

Conditions: none

Do not call squared distance the side length or reorder endpoint labels because of the chosen vertex.

Step identifiers and dependencies

Rule: opposite_side_square_not_length · Uses: G001, S016

Reverse checks

  • S017 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S016 · premise_and_result_audit — Recompute opposite side squared distance with exact rational arithmetic, not rounded decimals.
  • S015 · premise_and_result_audit — Recompute opposite side difference squared1 with exact rational arithmetic, not rounded decimals.
  • S014 · premise_and_result_audit — Recompute opposite side coordinate difference1 with exact rational arithmetic, not rounded decimals.
  • S013 · premise_and_result_audit — Recompute opposite side difference squared0 with exact rational arithmetic, not rounded decimals.
  • S012 · premise_and_result_audit — Recompute opposite side coordinate difference0 with exact rational arithmetic, not rounded decimals.
  • S011 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S010 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S009 · premise_and_result_audit — Recompute ABC signed determinant with exact rational arithmetic, not rounded decimals.
  • S008 · premise_and_result_audit — Recompute ABC cross negative term with exact rational arithmetic, not rounded decimals.
  • S007 · premise_and_result_audit — Recompute ABC cross positive term with exact rational arithmetic, not rounded decimals.
  • S006 · premise_and_result_audit — Recompute ABC second vector component1 with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute ABC second vector component0 with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute ABC first vector component1 with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute ABC first vector component0 with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S001 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.

Result

([2, 3], 1)

The full substitutions and premise checks give the original answer; source identity,format and status are unchanged.

This question review and source binding

Review date: 2026-10-26

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: d84dfd6290ea6fd624fbfa9694c72a099ed17453c06ac85089972a98a3049960
  • candidate record SHA-256: cbe3369e5bec89cd0cbc17904461d8bd553169a2eeb601a12bfb778305c4e6da
  • semantic review receipt SHA-256: 90dbc494b2d34ef51f412dcff63cfcc1a2215d038bff71f38f5dded4c64faf00
  • question-first witness SHA-256: b72a3b8bcf10f584396e0dd5198c657b0934a71864e5a3fa6321d7a613aef9f9
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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