The triangle has one angle of 100 degrees, and the other two are equal. We know that the angles of a triangle always add up to 180. To find the measurement of angle 1 and 2, let's solve for this equation. 2x + 100 = 180, where x=angle 1 = angle 2. Subtract 100 from both sides 2x = 80 Divide both sides by 2 x = 40