In the diagram, the radius of the circle is equal to the length AB. Can you find the size of angle ACB?

Prove that these two lengths are equal.

Weekly Problem 34 - 2008

What is the area of the region common to this triangle and square?

Weekly Problem 44 - 2009

A garden has the shape of a right-angled triangle. A fence goes from the corner with the right-angle to a point on the opposite side. How long is the fence?

Just from the diagram, can you work out the radius of the smaller circles?