It says the circumference is pi/2; so undo that by using the circumference formula to solve for r(radius);
2pi*r=pi/2 pi crosses each other off, making 2r=1/2 (When something crosses itself out it becomes a 1) 2r=1/2 r=.25 (because 1/2 is 0.5, and 0.5 divided by 2 is .25)
Now use the r you have in the area formula. a=pi*r^2 .25 squared is .0625
1 divided by .0625 is 16, so now you have a=pi*.0625 this will get you 1/16th of pi, or pi divided by 16.
