Wood Pile Perimeter

Weekly Problem 30 - 2011
Three touching circles have an interesting area between them...
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Problem

Image
Wood Pile Perimeter



The diagram shows three touching circles each of radius $5$cm and a line which touches two of them.

 

Find, in terms of $\pi$, the total perimeter of the two shaded shapes.

 

 

 

If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.