Finding radius given three points?

[nowayhosesay]

How do I go about finding the radius of the circle, I seem to be stumped on this question?

*dimensions in attachment are not to scale, just a rough sketch.

 

[Dickfore]

so, this segment that is 3 cm long, is it on a line satisfying some special relation with respect to the line on which the 10 cm segment lies?

 

[phinds]

There is a format here for posting this kind of homework assignment. Read the forum rules. When you have stated what you know and what you have tried so far someone will be able to give you help with what you're having trouble with. Just saying "I seem to be stumped" looks a lot like "gee guys, how about just spoon feeding me the answer to this so that I don't have to think". I'm not trying to be rude with this, just help you understand how this forum works.