1099. 
A truncated cone has horizontal bases with radii and . A sphere is tangent to the top, bottom, and lateral surface of the truncated cone. What is the radius of the sphere?
This problem is copyrighted by the American Mathematics Competitions.

Instructions for entering answers:
For questions or comments, please email markan@eudelic.com.
Try our new, free contest math practice test. All new, neverseenbefore problems.
I offer online AMC/AIME classes periodically. Join the mailing list to be informed next time they're offered.
Private coaching is also available.