Chapter 12: Vectors and the Geometry of Space - Section 12.6 - Cylinders and Quadric Surfaces - Exercises 12.6 - Page 732: 17

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In the xy plane $(z=0)$: $\displaystyle \frac{x^{2}}{1^{2}}+\frac{y^{2}}{3^{2}}=1\qquad$ ... ellipse In the xz plane ($y=0)$ $\displaystyle \frac{x^{2}}{1^{2}}+\frac{z^{2}}{3^{2}}=1\qquad$ ... ellipse In the yz plane $(x=0):$ $ y^{2}+z^{2}=3^{2}\qquad$ ... circle