Question

In the diagram, what is the measure of angle 1?

Answer 1

C

Explanation:

The adjacent angle to the left of 9x is 180 - 9x ( straight angle )

180 - 9x and 3x are corresponding angles and are congruent , then

3x = 180 - 9x ( add 9x to both sides )

12x = 180 ( divide both sides by 12 )

x = 15

Then

∠ 1 and 180 - 9x are vertically opposite angles and are congruent, so

∠ 1 = 180 - 9(15) = 180 - 135 = 45° → C