calculus $2$ c$)$ Use the "washer method" to find the volume of a sphere of radius $R$ with a hole of radius $r$ cut rough the middle of it$.($Hint: $($:$(R^2-r^2)\sqrt[\phantom{2}]{R^2-r^2}=(R^2-r^2{)}^{\frac{3}{2}}\}$

d$)$ Use the method of "cylindrical shells" to find the volume of a sphere of radius $R$ with a hole of radius $r$ cut through the middle of it$.($Hint: You must use a $u-$substitution.$)$