Thomas' Calculus 13th Edition

Published by Pearson
ISBN 10: 0-32187-896-5
ISBN 13: 978-0-32187-896-0

Chapter 11: Parametric Equations and Polar Coordinates - Section 11.7 - Conics in Polar Coordinates - Exercises 11.7 - Page 685: 7

Answer

$F(\pm\sqrt{3},0)$ Eccentricity$:\qquad e =\displaystyle \frac{\sqrt{3}}{3}$ Directrices$:\quad x=\pm 3\sqrt{3}$ Graph:

Work Step by Step

Write in standard form. $6x^{2}+9y^{2}=54\qquad /\div 54$ $=\displaystyle \frac{x^{2}}{9}+\frac{y^{2}}{6}=1,\qquad a=6,b=\sqrt{6}$ The major axis is horizontal. $c=\sqrt{a^{2}-b^{2}}=\sqrt{9-6}=\sqrt{3}$ $F(\pm\sqrt{3},0)$ Eccentricity$:\qquad e=\displaystyle \frac{c}{a}=\frac{\sqrt{3}}{3}$ Directrices$:\displaystyle \quad x=0\pm\frac{a}{e}$ $x=\displaystyle \pm\frac{3}{\frac{\sqrt{3}}{3}}$ $x=\pm 3\sqrt{3}$
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