Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 8 - Section 8.4 - Plane Curves and Parametric Equations - 8.4 Exercises - Page 617: 20

Answer

(a) See the graph. (b) $y^2-x^2=1,~~y\geq1$

Work Step by Step

(a) $t=\frac{\pi}{4}$: $x=cot\frac{\pi}{4}=1$ $y=csc\frac{\pi}{4}=\sqrt 2$ Point: $(1,\sqrt 2)$ $t=\frac{\pi}{2}$: $x=cot\frac{\pi}{2}=0$ $y=csc\frac{\pi}{4}=1$ Point: $(0,1)$ $t=\frac{3\pi}{4}$: $x=cot\frac{3\pi}{4}=-1$ $y=csc\frac{3\pi}{4}=\sqrt 2$ Point: $(-1,\sqrt 2)$ When $t→0$ both $x$ and $y$ $→∞$. So, $x\geq1$ and $y\geq0$ When $t→\pi$ both $x$ and $y$ $→-∞$. So, $x\geq1$ and $y\geq0$ (b) $x=cot~t$ $x^2=cot^2t$ $y=csc~t$ $y^2=csc^2t$ $csc^2t=cot^2t+1$ $y^2=x^2+1$ $y^2-x^2=1$
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