Practice On Your Own A solid lies between planes perpendicular to the $x-$axis at $x=-6$ and $x=6.$ The cross$-$sections are squares perpendicular to the $x-$axis whose bases run from the semicircle $y=-\sqrt[\phantom{2}]{36-x^2}$ to the semicircle $y=\sqrt[\phantom{2}]{36-x^2}.$

Draw the base of the solid. Beside your base draw a representative cross$-$section. Be sure to label the common length on both the base and cross$-$section.