Question

In ΔSIM, if IS=IM and ∠S = 78°, what is the exact measure of ∠M?

A. 180°
B. 24°
C. 80°
D. 78°

Answer 1

D

Explanation:

since IS = IM then Δ SIM is isosceles with the 2 base angles being congruent , then

∠ M = ∠ S = 78°

Answer 2

D. 78°

Explanation:

In the given isosceles triangle, the congruent base angles are ∠S and ∠M. If the measure of angle S is 78°, then the measure of angle M is 78°.