2005 PMWC Problems/Problem T7


Skipper’s doghouse has a regular hexagonal base that measures one metre on each side. Skipper is tethered to a 2-metre rope which is fixed to a vertex. What is the area of the region outside the doghouse that Skipper can reach? Calculate an approximate answer by using $\pi=3.14$ or $\pi=22/7$.


The big sector has a radius of 2 and is 2/3 of the total circle that it used to be a part of, and thus has an area of $4\pi\cdot\frac{2}{3}=\frac{8}{3}\pi$. The two little sectors each have radius 1 and are 1/6 the total area of their circle, so the area of each of those is $\frac{\pi}{6}$. Adding, we get $\frac{8}{3}\pi+\frac{\pi}{6}+\frac{\pi}{6}=3\pi$. Then approximate.

See also

2005 PMWC (Problems)
Preceded by
Problem T6
Followed by
Problem T8
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T: 1 2 3 4 5 6 7 8 9 10