Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Chapter 10 - Analytic Geometry - 10.2 The Parabola - 10.2 Assess Your Understanding - Page 647: 32

Answer

$(y+2)^2=8(x-4)$ Latus rectum points: $(6,-6),(6,2)$ See graph

Work Step by Step

We are given the parabola: Focus: $(6,-2)$ Vertex: $(4,-2)$ Because the vertex and the focus have the same $y$-coordinate, the parabola is horizontal. Its standard equation is: $(y-k)^2=4p(x-h)$ Use the coordinates of the vertex to determine $h,k$: $(h,k)=(4,-2)$ $h=4$ $k=-2$ Determine $p$ using the coordinates of the focus: $(h+p,k)=(6,-2)$ $(4+p,-2)=(6,-2)$ $4+p=6$ $p=2$ Determine the parabola's equation: $(y+2)^2=4(2)(x-4)$ $(y+2)^2=8(x-4)$ Determine the two points defining the latus rectum: $x=6$ $(y+2)^2=8(6-4)$ $(y+2)^2=16$ $y+2=\pm 4$ $y+2=-4\Rightarrow y_1=-6$ $y+2=4\Rightarrow y_2=2$ $\Rightarrow (6,-6),(6,2)$ Plot the points and graph the parabola:
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