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Parallel Lines Transversal Angles Test Answer Key with Scoring – Geometry

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Last updated: October 22, 2026 · Written by the Math Made Easy math teachers

Geometry Math Test Answer Keys – Mathbot, the Math Made Easy robot coach, with free printable test answer keys for Geometry

Looking for a parallel lines transversal angles test answer key? Then this answer key gives the solutions and the scoring guide of the Geometry test on Parallel Lines Cut by a Transversal. Each solution shows the angle relationship, the equation and the scoring split. Where a reason is required, name the theorem or definition used rather than describing the picture.

Standards: G-CO.C.9 · Level: Grade 10 Geometry

Question 2 Find three angles (3 points)

abt119°61°61°119°119°61°61°119°
Solved figure for Question 2.
  1. ∠2 and ∠6 are corresponding: 61°.
  2. ∠4 and ∠2 form a linear pair: 180° − 61° = 119°.
  3. ∠7 is vertical to ∠6, so it equals 61°.

(a) 61°, (b) 119°, (c) 61°

Scoring: 1 point per angle.

Question 3 Alternate interior equation (2 points)

Alternate interior angles are equal: 4x + 11 = 6x − 19, so 30 = 2x and x = 15. Each angle is 4(15) + 11 = 71°, and 6(15) − 19 = 71°.

x = 15; 71°

Scoring: 1 point for x, 1 point for the measure.

Question 4 Decide if lines are parallel (3 points)

  1. Parallel: congruent corresponding angles.
  2. Not parallel: 64° ≠ 66°, so the alternate interior angles are not congruent.
  3. Parallel: 105° + 75° = 180°, so the same-side interior angles are supplementary.

(a) parallel, (b) not parallel, (c) parallel

Scoring: 1 point per part (answer and reason).

Question 5 Parallel with same-side angles (2 points)

The angles must be supplementary: 7x + 4 + 5x + 20 = 180, so 12x + 24 = 180 and x = 13. The angles are 7(13) + 4 = 95° and 5(13) + 20 = 85°.

x = 13; 95° and 85°

Scoring: 1 point for x, 1 point for both angles.

Question 6 Prove lines parallel (3 points)

Statement Reason
1. ∠2 ≅ ∠7 Given
2. ∠7 ≅ ∠6 Vertical angles are congruent
3. ∠2 ≅ ∠6 Transitive Property of congruence
4. a ∥ b Converse of the Corresponding Angles Theorem

Scoring: 1 point for statements 2 and 3 with reasons, 1 point for the conclusion, 1 point for correct order.

Question 7 Equidistant point (3 points)

  1. 2x + 9 = 4x − 7, so 16 = 2x and x = 8.
  2. PA = 2(8) + 9 = 25.
  3. The midpoint is 24 from each end and the bisector is perpendicular to AB, so the distance is √(25² − 24²) = √49 = 7.

x = 8; PA = 25; distance 7

Scoring: 1 point per part.

Question 8 Crossing bike lanes (2 points)

The matching (corresponding) angle on the second lane is also 38°. An angle on the same side between the lanes is supplementary to 38°, so it measures 180° − 38° = 142°.

38° and 142°

Scoring: 1 point for each angle with a valid reason.