Question

if two angles of a triangle have measures of 20 and 40 degrees, what is the measure of the third.

Answer 1

The sum of all angles in a triangle is 180.

AngleA+AngleB+AngleC=180
20+40+AngleC=180
AngleC=120

Answer 2

All 3 angles must add up to 180. So 40 + 20 = 60. Subtract that from 180 and you get 120. There is your answer