Question

∡C and ∡D are supplementary angles. If m∡D is nine less than twice m∡C, find m∡D.

Answer 1

D is 117

Explanation:

Let the measure of angle C be x

The measure of D is 9 less than twice C

Mathematically that is 2x-9

If both are supplementary, they add up to be 180

Thus;

x + 2x - 9 = 180

3x = 180 + 9

x = 189/3

x = 63

Recall;

D = 2x-9= 2(63) -9 = 126 -9 = 117