MathDB
2006 AMC 10 #6

Source:

August 20, 2011
geometryperimeter

Problem Statement

A region is bounded by semicircular arcs constructed on the side of a square whose sides measure 2/π 2/\pi , as shown. What is the perimeter of this region?
[asy] size(90); defaultpen(linewidth(0.7)); filldraw((0,0)--(2,0)--(2,2)--(0,2)--cycle,gray(0.5)); filldraw(arc((1,0),1,180,0, CCW)--cycle,gray(0.7)); filldraw(arc((0,1),1,90,270)--cycle,gray(0.7)); filldraw(arc((1,2),1,0,180)--cycle,gray(0.7)); filldraw(arc((2,1),1,270,90, CCW)--cycle,gray(0.7));[/asy]
<spanclass=latexbold>(A)</span>4π<spanclass=latexbold>(B)</span>2<spanclass=latexbold>(C)</span>8π<spanclass=latexbold>(D)</span>4<spanclass=latexbold>(E)</span>16π <span class='latex-bold'>(A) </span>\frac {4}\pi\qquad<span class='latex-bold'>(B) </span>2\qquad<span class='latex-bold'>(C) </span>\frac {8}\pi\qquad<span class='latex-bold'>(D) </span>4\qquad<span class='latex-bold'>(E) </span>\frac{16}{\pi}