In ΔDEF, an exterior angle at F is (8x + 15). If the two non-adjacent interior angles are (4x + 5) and (3x + 20), find the value of that exterior angle (in degrees).
95
A measure of an exterior angle of a triangle is equal to the sum of the measures of the interior opposite angles.
8x + 15= (4x + 5) + (3x + 20)
8x + 15 = 7x + 25
8x – 7x = 25 – 15
x = 10
So, exterior angle = 8x + 15 = 8 × 10 + 15 = 95∘