c=2pi*r; circumference formula
a=pi*r^2; area formula
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.
(1/16th if pi is the same as pi divided by 16)
.0625pi=pi/16