Question

Find the measure of the angle or arc indicated. Assume that lines that appear to be diameters are actual diameters.

Answer 1

Like the problem states, lines that appear to be diameters can be assumed to be diameters.

AC looks like a diameter, so arc AC is 180 degrees on each side of the circle.

on the bottom half of the circle, arc AC is intersected by angle B on the perimeter. so angle B is one half arc AC or one half of 180.

at this point you have angle A and angle B, and you know angles A B and C make up a full triangle, so angle C would be 180 - angle A - angle B