Question

In this figure, ∠a and ∠b are

A. complementary.
B. supplementary.
C. vertical.
D. equal.

Answer 1

angles a and b are supplementary because they form a straight line

Answer 2

In this figure, ∠A and ∠B would be supplementary, or Choice B. This is because the angles comprise a straight angle.

Essentially, if you took away the line dividing angles A and B, then you would have a perfectly straight angle, which means that the angles are supplementary. Additionally, this means that their measures add to 180°.