Calculus 10th Edition

Published by Brooks Cole
ISBN 10: 1-28505-709-0
ISBN 13: 978-1-28505-709-5

Chapter 10 - Conics, Parametric Equations, and Polar Coordinates - Review Exercises - Page 742: 23

Answer

$\frac{{{x^2}}}{{49}} - \frac{{{{\left( {y + 1} \right)}^2}}}{{32}} = 1{\text{ }}$

Work Step by Step

$$\eqalign{ & {\text{Vertices }}\left( { \pm 7, - 1} \right) \cr & {\text{Foci: }}\left( { \pm 9, - 1} \right) \cr & y{\text{ is constant}}{\text{, then the equation of the hyperbola is }} \cr & \frac{{{{\left( {x - h} \right)}^2}}}{{{a^2}}} - \frac{{{{\left( {y - k} \right)}^2}}}{{{b^2}}} = 1{\text{ }}\left( {\bf{1}} \right) \cr & \cr & {\text{Foci: }}\left( {h - c,k} \right){\text{ and }}\left( {h + c,k} \right) \cr & h - c = - 9,{\text{ }}h + c = 9 \to h = 0,{\text{ }}c = 9 \cr & {\text{Vertices: }}\left( {h - a,k} \right){\text{ and }}\left( {h + a,k} \right) \cr & h - a = - 7,{\text{ }}h + a = 7 \to h = 0,{\text{ }}a = 7 \cr & \cr & {c^2} = {a^2} + {b^2},{\text{ then}} \cr & {b^2} = {c^2} - {a^2} \cr & {b^2} = {9^2} - {7^2} \cr & {b^2} = 32 \cr & \cr & {\text{Substituting into }}\left( {\bf{1}} \right) \cr & \frac{{{{\left( {x - 0} \right)}^2}}}{{49}} - \frac{{{{\left( {y - \left( { - 1} \right)} \right)}^2}}}{{32}} = 1{\text{ }} \cr & \frac{{{x^2}}}{{49}} - \frac{{{{\left( {y + 1} \right)}^2}}}{{32}} = 1{\text{ }} \cr} $$
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