Bluebook SAT Test Lines, Angles, and Triangles 1

Question 1

Two parallel lines are cut by a transversal. One co-interior (same-side interior) angle is 65°. What is the other co-interior angle?

Accepted Answer

115°

Answer

Co-interior angles are supplementary: 180° − 65° = 115°.

Question 2

In a triangle, two angles measure 47° and 83°. What is the third angle?

Accepted Answer

50°

Answer

Third angle = 180° − 47° − 83° = 50°.

Question 3

Two lines intersect and one angle measures 72°. What is the vertically opposite angle?

Accepted Answer

72°

Answer

Vertical angles are equal; the opposite angle is 72°.

Question 4

A transversal crosses two parallel lines. One corresponding angle is 110°. What is the other corresponding angle?

Accepted Answer

110°

Answer

Corresponding angles formed by parallel lines are equal: 110°.

Question 5

An isosceles triangle has a vertex angle of 40°. What is each base angle?

Accepted Answer

70°

Answer

2x + 40 = 180 → x = 70°.

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