In the circle below, segment AB is tangent to circle C and segment DE is parallel to segment AB.
If arc DE is 78 degrees, what is the measure of arc AD?

Question

In the circle below, segment AB is tangent to circle C and segment DE is parallel to segment AB. 
If arc DE is 78 degrees, what is the measure of arc AD?

anonymous · Answer

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anonymous · Answer

Oh wait I think I got it. I got 141 degrees, is that right?

anonymous · Answer

Yes. Because point A is halfway between D and E along the circumference of the circle. The total angle of a circle is 360. We know the arc length between DE. Therefore, AD = (360 - 78)/2

anonymous · Answer

Oh good! That's what I thought. I think I just posted this question without really reading it, and thinking it was difficult at first. Thanks!

anonymous · Answer

No problem. Keep up the good work!