Note: we can see that if we complete the circle, the radius is 15 cm.
First find the area of the square.
15*15=225 cm^2
Now find the area of the white area, which is a quarter circle.
S PR = 225π/4
The area of the shaded area should then be 225-(225/4)π cm^2
If we take 3/14 for π, then we get answer
225-176.625
=48.375 cm²