Use Pappus's Theorem to compute y y for the upper half of the disk x 2 + y 2 a 2 ,

Use Pappus's Theorem to compute $\overline{y}$ for the upper half of the disk $x^2+y^2\le a^2,y\ge 0$. Hint: The disk revolved about the $x$-axis is a sphere.

B- a b L