Question

In the diagram below, if < 2 is congruent to < 8, then lines a and b are parallel. What would the reason be for this statement?

Answer 1

When two parallel lines are cut by a transversal, then the alternate exterior angles angles are congruent. Looking at the given figure,

a and b are parallel lines and t is a transversal. This means that angle 2 and 8 are alternate angles. Since they lie on the exterior of both lines a and b, they are alternate exterior angles. The correct option is

Alternate exterior angles are congruent