Myōjōrinji Temple #6
This problem was posted at Myōjōrinji temple in Gifu Prefecture in 1865. It is located on the Sangaku Archive at [URL].
Statement
In the diagram below, show that the pin circles, and also the orange circles, have one-sixth the radius of the big circle.
Problem notes
One of the useful triangles in this problem is oblique (non-right). The Law of Cosines may be helpful here.