Answer:
x^2 / 4pi
Step-by-step explanation:
The area of a circle is (pi x r)^2
The circumference of a circle is 2pi x r
The find the radius, you need to divide x by 2pi, so x / 2pi
Then just plug it in as the radius:
(pi x (x / 2pi))^2 = x^2 / 4pi
75%
100-25 = 75