Hi!

Today we had a test at school and I had this interesting question ,that I didn't know how to answer.

So it was said: A sphere is touching all 3 edges of a right triangle, its edges are 9 and 12 cm long. The distance from the sphere's center to the triangle plane is 10cm. How long is the radius of the sphere?

I don't know if I made the picture right, but I think it should look like this:

http://img266.imageshack.us/img266/840/testol.jpg
Somewhere I heard that if it both edges were the same size (for example, 9 and 9) then the distance and radius would be the same size.

How could I get the radius? The answer should be 12.25 cm, but not sure.