The figure shown has two parallel lines cut by a transversal:

Question

A pair of parallel lines is shown, crossed by a transversal. Angles are identified as 1, 2, 3, 4, 5, 6, 7, and 8. Angles 1-4 are on the top line clockwise from upper left. Angles 5-8 are on the lower line clockwise from upper left.

Which angle is an alternate interior angle to ∠3?

∠2
∠6
∠5
∠8

Answer 1

In a figure with two parallel lines and a transversal, alternate interior angles are the pairs of angles that are on opposite sides of the transversal and inside the parallel lines.

Given the angles you described:

• Angles 1, 2, 3, and 4 are on the upper line.
• Angles 5, 6, 7, and 8 are on the lower line.

∠3 is located on the upper line, and we need to find the angle that is an alternate interior angle to ∠3.

The alternate interior angle to ∠3 is located on the opposite side of the transversal and under the parallel lines. That means we are looking for the angle below ∠3 that is on the lower line.

In this case, ∠5 is positioned directly below ∠3, making it the alternate interior angle.

Thus, the angle that is an alternate interior angle to ∠3 is:

∠5