Question

15. Find m∠DEC (the picture is not drawn to scale).

Answer 1

m∠DEC = 123°

Explanation:

First we need to solve for x the equation: x = (x - 45) + (x-12)

x = (x - 45) + (x-12) ⇔ x = 2x -57 ⇔ 0 = x - 57 ⇔ x = 57

since m∠DEC = 180 - x then m∠DEC = 180 - 57 = 123