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Question 2904: Specified Axial Point on a Circle

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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R0004-02904 · q-20261005-advance-20261006-r05-circle-0079

Original question and givens

Use one equal-unit orthonormal Euclidean Cartesian frame. The circle boundary has center O=(-9, 0) and radius r=3≥0. Change only its x-coordinate by (-1)r. Give the resulting axial boundary point as an ordered pair.

  • G001 — Use one equal-unit orthonormal Euclidean Cartesian frame. The circle boundary has center O=(-9, 0) and radius r=3≥0. Change only its x-coordinate by (-1)r. Give the resulting axial boundary point as an ordered pair.

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

orthonormal equal-length units;r=3≥0

After

C={P:distance(P,O)=r} is a boundary,not a filled disk

Conditions: none

The circle is the boundary at distance exactly r from the center,not the filled disk.For r=0 use the degenerate singleton{O},with no inside points and diameter length0.

Step identifiers and dependencies

Rule: circle_boundary_convention · Uses: G001

S002 · calculation

Before

radius squared := square(3)

After

radius squared = 9

Conditions: none

The square of the nonnegative radius is the distance-comparison threshold.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S001

S003 · calculation

Before

signed radial displacement := mul(-1, 3)

After

signed radial displacement = -3

Conditions: none

Multiply the radius by the specified direction sign;only the selected coordinate changes.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

point coordinate0 := sum(-9, -3)

After

point coordinate0 = -12

Conditions: none

Add displacement to the center;the unselected coordinate adds0 and is retained.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

point coordinate1 := sum(0, 0)

After

point coordinate1 = 0

Conditions: none

Add displacement to the center;the unselected coordinate adds0 and is retained.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

coordinate difference0 := sub(-12, -9)

After

coordinate difference0 = -3

Conditions: none

Subtract the center coordinate from the point coordinate;do not square absolute coordinates instead.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · calculation

Before

coordinate square0 := square(-3)

After

coordinate square0 = 9

Conditions: none

Square this coordinate difference;a negative difference still contributes a nonnegative square.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S006

S008 · calculation

Before

coordinate difference1 := sub(0, 0)

After

coordinate difference1 = 0

Conditions: none

Subtract the center coordinate from the point coordinate;do not square absolute coordinates instead.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S007

S009 · calculation

Before

coordinate square1 := square(0)

After

coordinate square1 = 0

Conditions: none

Square this coordinate difference;a negative difference still contributes a nonnegative square.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S008

S010 · calculation

Before

squared distance := sum(9, 0)

After

squared distance = 9

Conditions: none

In an orthonormal equal-unit frame,the Pythagorean relation adds the squared differences.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S009

S011 · implies

Before

squared distance=9;r²=9

After

(-12, 0)

Conditions: none

Substitute back to check circle membership;when r=0 every specified axis and direction yields the center.

Step identifiers and dependencies

Rule: axial_point_membership_audit · Uses: G001, S010

Reverse checks

  • 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 — Recompute squared distance with exact rational arithmetic, not rounded decimals.
  • S009 · premise_and_result_audit — Recompute coordinate square1 with exact rational arithmetic, not rounded decimals.
  • S008 · premise_and_result_audit — Recompute coordinate difference1 with exact rational arithmetic, not rounded decimals.
  • S007 · premise_and_result_audit — Recompute coordinate square0 with exact rational arithmetic, not rounded decimals.
  • S006 · premise_and_result_audit — Recompute coordinate difference0 with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute point coordinate1 with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute point coordinate0 with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute signed radial displacement with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Recompute radius squared with exact rational arithmetic, not rounded decimals.
  • S001 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.

Result

(-12, 0)

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: cbbe9b41c07ed3cbd4dec8a6e72cd6dccc33790fe8711ede867781e52224df6b
  • candidate record SHA-256: a8f59ef9a481b9475168bcc8f2542e9dfc844e6b4e342767cf1613c470032841
  • semantic review receipt SHA-256: 312ae86315346b8955842a547cb2d09246e1f826755f72c2a51f042e5c7d5c56
  • question-first witness SHA-256: 831f449ed41ff9144a290e534aa32adf7252d15b81c16ed5886a7dfd65dee70c
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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