Let the function s be defined so that s(x) is the area of a semicircle with diameter x. if s(6) + s(8) = s(b). What is the value of b ?
Radius of semicircle is x/2, so s(x) = (1/2)pi(x/2)^2 = (pix^2)/8. Use this to compute s(6) + s(8). Solve for b. You should get b = 10.
You can also get b = 10 simply by using the fact that 6^2 + 8^2 = 10^2.