Points A, B and C are the centres of three circles, each one of
which touches the other two. Prove that the perimeter of the
triangle ABC is equal to the diameter of the largest circle.
Weekly Problem 37 - 2013
The diagram shows two semicircular arcs... What is the diameter of the shaded region?
Two circles are enclosed by a rectangle 12 units by x
The distance between the centres of the two circles is
How big is x?