Question

Refer to the figure to find the following measure.

If mAD = 20° and m BC = 30°, then angle 1=
25°
5°
10°

Answer 1

∠ 1 = 25°

Explanation:

the measure of the chord- chord angle 1 is half the sum of the measures of the arcs intercepted by the angle and its vertical angle , that is

∠ 1 =
`(1)/(2)` (AD + BC) =
`(1)/(2)` (20 + 30)° =
`(1)/(2)` × 50° = 25°