1982 AHSME Problems/Problem 4

by mathhayden (bad)

perimeter=2r+pi2r=2r(pi+1)

area=[pi(r^2)]/2

make them equal & solve for r: pi(r^2)/2=2r(pi+1) pi(r^2)=4r(pi+1) (r^2)=4r[(pi+1)/pi] r=4(pi+1)/pi

=   Ans.