Problem

Find the measure of the marked angle. See Example.EXAMPLE Finding Angle MeasuresRefer to t...

Find the measure of the marked angle. See Example.

EXAMPLE Finding Angle Measures
Refer to the appropriate figure in each part.
(a) Find the measure of each marked angle in Since the marked angles are vertical angles, they have equal measures.
Replace x with 12 in the expression for the measure of each angle.
Each angle measures 67°.
FIGURE 13
FIGURE 14
(b) Find the measure of each marked angle in The measures of the marked angles must add to 180° because together they form a straight angle. (They are also supplements of each other.)
Replace x with 30 in the expression for the measure of each angle.
The two angle measures are 60° and 120°.