Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 11 - Section 11.2 - Ellipses - 11.2 Exercises - Page 797: 14

Answer

(a) Vertices: $(0,±8)$ Foci: $(0,±\sqrt {55})$ Eccentricity: $e=\frac{\sqrt {55}}{8}$ (b) Length of the major axis: $2a=16$ Length of the minor axis: $2b=6$ (c)

Work Step by Step

$\frac{x^2}{9}+\frac{y^2}{64}=1$ $\frac{x^2}{3^2}+\frac{y^2}{8^2}=1$ The major axis is vertical. Equation of an ellipse when major axis is vertical (center at the origin): $\frac{x^2}{b^2}+\frac{y^2}{a^2}=1$ So: $a=8$ $b=3$ $c^2=a^2-b^2=8^2-3^2=64-9=55$ $c=\sqrt {55}$ (a) Vertices: $(0,±a)=(0,±8)$ Foci: $(0,±c)=(0,±\sqrt {55})$ Eccentricity: $e=\frac{c}{a}=\frac{\sqrt {55}}{8}$ (b) Length of the major axis: $2a=16$ Length of the minor axis: $2b=6$
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