Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 8 - Section 8.1 - Polar Coordinates - 8.1 Exercises - Page 593: 31

Answer

The point in rectangular coordinates is $(1,-1)$

Work Step by Step

$(\sqrt{2},-\pi/4)$ The point has $r=\sqrt{2}$ and $\theta=-\dfrac{\pi}{4}$. The formulas for converting polar to rectangular coordinates are $x=r\cos\theta$ and $y=r\sin\theta$ Substitute the known values into the formulas to obtain $x$ and $y$: $x=r\cos\theta$ $x=(\sqrt{2})\cos\Big(-\dfrac{\pi}{4}\Big)=(\sqrt{2})\Big(\dfrac{\sqrt{2}}{2}\Big)=\dfrac{(\sqrt{2})^{2}}{2}=\dfrac{2}{2}=1$ $y=r\sin\theta$ $y=(\sqrt{2})\sin\Big(-\dfrac{\pi}{4}\Big)=(\sqrt{2})\Big(-\dfrac{\sqrt{2}}{2}\Big)=-\dfrac{(\sqrt{2})^{2}}{2}=-\dfrac{2}{2}=-1$ The point in rectangular coordinates is $(1,-1)$
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