if you have a pizza with a diameter of 20 that is cut equally into 4 pieces, one way horizontal and one way vertical. how do i figure out where to place 2 non-center vertical cuts so that the pizza has 8 equal parts?

Question

i found the area for the circle to be 314.159 (divided by 8 = 39.269) i did the integral from 0 to x of sqrt(100-x^2) = 39.269 and tried to solve for x. i get a negative answer.

how do i solve this problem?