Question

Two parallel lines are intersected by a third line so that angles 1 and 5 are congruent.

2 parallel horizontal lines are intersected by a third line. On the first horizontal line where the third line intersects, 4 angles are created. Labeled clockwise, from uppercase left, the angles are 1, 2, 4, 3. On the second horizontal line, where the third line intersects, 4 angles are created. Labeled clockwise, from uppercase left, the angles are 5, 6, blank, blank.
Which statement is true about angles 3 and 5?

They are acute.
They are congruent.
They are complementary.
They are supplementary.

Answer 1

They are supplementary.

Reason: Angles 1 and 3 form a linear pair at the first intersection, so 1 + 3 = 180°. Since 1 ≅ 5, replace 1 with 5 to get 5 + 3 = 180°, so angles 3 and 5 are supplementary.