Hi there!
After I read your question my intuall thoughts were I know this question. So i decided to help you by giving you i think everything you need to answer this yourself. So here is my points in order in which they should help you.
1. Because the circle is tuching both of the trapezoid bases what does this tell you about the raidious and the height?
2. Next find the sides of AD and BC
3. Use rule of tangents (google if you dont know)
4.Draw a line from points A and B down to line DC. Use pytagorean theorem
5. REMBER that line that you drew in the previous step is also 2 times the radious.
6. After you simplify the equation you get from these last 2 steps you prove your point.
Notes: Rember AAS congruence and please try your best to word your answer in the right way make sure you prove why each step should happen.
I understand were you are coming from so I gave you hints not an answer. I dont want to hand you an answer because of two reasions. 1. because you should figure it out on your own (with help because this is tricky) 2. Because i dont know how to word this without telling you what I wrote my self.
Please take my hints and figure out your answer.
Hope this helped you!!!
~Wolf :D
