In order to find the area of the shaded area, we have to find the area of the entire square, unshaded and shaded and then divide it by the area of the circle.
First, let's find the area of the square:
80*80 = 6400
That wasn't too bad, was it?
The equation to solve for the area of a circle is πr^2.
Since we know that the diameter of the circle is 80, we simply divide it by 2 to find the radius, which is 40.
40^2 * π = 1600π
Turn π into 3.14 to completely solve for the area:
1600*3.14 = 5024
Subtract the area of the square by the area of the circle:
6400 - 5024 = 1376
The area of the shaded part of the square is 1376 units squared.
Good luck!