Question

Two angles of a triangle measure 12º and 40°.

What is the measure of the third angle of the triangle?
A. 38
B. 48
C. 128
D. 308°

Answer 1

The sum of the interior angles in each triangle is 180 degrees.

so :

12 + 40 + x = 180

52 + x = 180

x = 180 - 52

x = 128

so the third angle of the triangle is 128 degrees which means C is correct.