Question

In circle O. AD and BE are diameters. The measure of arc AB is 55° and the measure of arc CD is 25° B с F D E What is the measure of BC ? 090 O 110 O 100 O 80​

Answer 1

100°

Explanation:

the total of all angles around O on one side of AD is 180° (as that would represent a half-circle).

and the sum of the arc angles AB + BC + CD covers the whole 180°.

so, we have

180 = 55 + BC + 25

180 = 80 + BC

BC = 100°