Question

If arc AB= 70, how many degrees are in arc AD

Answer 1

the correct answer is C

Explanation:

Answer 2

notice, the chord BD is really a diametrical chord, namely a diameter, so it cuts the circle into two equal halves, each with 180°.

so the arcBAD = 180°, and arcBAD = arcBA + arcAD, we know arcAB = 70, so arcAD must be the remaining from 180 - 70 = 110.