Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 11 - Review - Exercises - Page 833: 19

Answer

(a) Center: $C(3,0)$ $V_1(3,-4)$ and $V_2(3,4)$ $F_1(3,-\sqrt 7)$ and $F_2(3,\sqrt 7)$ (b) Length of the major axis: $2a=8$ Length of the minor axis: $2b=6$

Work Step by Step

Equation of an ellipse with center at $(h,k)$ (major axis is vertical): $\frac{(x-h)^2}{b^2}+\frac{(y-k)^2}{a^2}=1$ $\frac{(x-3)^2}{9}+\frac{y^2}{16}=1$ $\frac{(x-3)^2}{3^2}+\frac{(y-0)^2}{4^2}=1$ $h=3$ $k=0$ Center: $C(3,0)$ $a=4$ $b=3$ $c^2=a^2-b^2=16-9=7$ $c=\sqrt 7$ The given equation can be obtained by shifting $\frac{x^2}{3^2}+\frac{y^2}{4^2}=1$ right 3 units. In this equation: Vertices: $V(0,±a)$ $V_1(0,-4)$ and $V_2(0,4)$ Foci: $F(0,±c)$ $F_1(0,-\sqrt 7)$ and $F_2(0,\sqrt 7)$ Now, shift these points 3 units: $V_1(3,-4)$ and $V_2(3,4)$ $F_1(3,-\sqrt 7)$ and $F_2(3,\sqrt 7)$ Length of the major axis: $2a=8$ Length of the minor axis: $2b=6$
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