Thomas' Calculus 13th Edition

Published by Pearson
ISBN 10: 0-32187-896-5
ISBN 13: 978-0-32187-896-0

Chapter 11: Parametric Equations and Polar Coordinates - Section 11.1 - Parametrizations of Plane Curves - Exercises 11.1 - Page 647: 10

Answer

$(x-1)^{2}+(y+2)^{2}=1,\ \ 1\leq x\leq 2$

Work Step by Step

From the parametric equation for x, we see that $x\in[1,2].$ (sine is positive in quadrants I and II, that is, when $t\in[0,\pi]$) From the parametric equation for $y$, we see that $y\in[-3,-1].$ (cosine varies from 1 to -1 in the first two quadrants) Rewriting the parametric equations, isolating $\sin t$ and $\cos t,$ $\left\{\begin{array}{l} x-1=\sin t\\ y+2=\cos t \end{array}\right.$ Square both equations and add: $ \fbox{$(x-1)^{2}+(y+2)^{2}=1,\ \ 1\leq x\leq 2$}$ - half of a circle of radius 1, centered at $(1,-2)$ To graph, create a table using several values for t, and then calculate $(x(t), y(t)),$ plotting the points as you go. Join with a smooth curve, noting the direction in which $t$ increases.
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