Calculus (3rd Edition)

Published by W. H. Freeman
ISBN 10: 1464125260
ISBN 13: 978-1-46412-526-3

Chapter 12 - Parametric Equations, Polar Coordinates, and Conic Sections - Chapter Review Exercises - Page 639: 41

Answer

The foci are ${F_1} = \left( {\sqrt 5 ,0} \right)$ and ${F_2} = \left( { - \sqrt 5 ,0} \right)$. The focal vertices are $\left( { \pm a,0} \right) = \left( { \pm 3,0} \right)$ and the minor vertices are $\left( {0, \pm b} \right) = \left( {0, \pm 2} \right)$.

Work Step by Step

By Theorem 1 of Section 12.5, this is the equation of an ellipse in standard position, where $a=3$ and $b=2$. Since $a>b>0$, we have $c = \sqrt {{a^2} - {b^2}} = \sqrt {9 - 4} = \sqrt 5 $ The foci are ${F_1} = \left( {\sqrt 5 ,0} \right)$ and ${F_2} = \left( { - \sqrt 5 ,0} \right)$. The focal vertices are $\left( { \pm a,0} \right) = \left( { \pm 3,0} \right)$ and the minor vertices are $\left( {0, \pm b} \right) = \left( {0, \pm 2} \right)$.
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