## Thomas' Calculus 13th Edition

In the xy plane $(z=0)$: $\displaystyle \frac{x^{2}}{2^{2}}+\frac{y^{2}}{2^{2}}=1\qquad$ ... circle In the xz plane ($y=0)$ $\displaystyle \frac{x^{2}}{2^{2}}+\frac{z^{2}}{4^{2}}=1\qquad$ ... ellipse In the yz plane $(x=0):$ $\displaystyle \frac{y^{2}}{2^{2}}+\frac{z^{2}}{4^{2}}=1\qquad$ ... ellipse