Question

Given the measure of arc dc is 120 the measure of arc ADC is?

Answer 1

the answer would be 120

Answer 2

120°

Explanation:

The arc ABC is twice that of the angle created at D. This is the central angle theorem extension.

So we can say that arc ABC = 2* 120 = 240

We know total circle angle is 360 degrees so, arc ADC + arc ABC = 360

Hence,

arc ADC + 240 = 360

arc ADC = 360 - 240 = 120