Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 8 - Application of Trigonometry - 8.5 Trigonometric (Polar) Form of Complex Numbers: Products and Quotients - 8.5 Exercises - Page 801: 38

Answer

$ \sqrt 3 -i$

Work Step by Step

The given complex number can be written in the rectangular form as follows: $r (\cos \theta +i \sin \theta) = a+i b$ Where, $a=r \cos \theta ; b =r \sin \theta $ Since, $\theta= 330^{\circ}$ is in the Fourth Quadrant , so the reference angle $= 360^{\circ}- 330^{\circ}= 30^{\circ}$ Because the is in Fourth Quadrant, so we will take it as a negative value. We know that $\sin (-\theta) =- \sin \theta$ and $\cos (-\theta) =\cos \theta$ Therefore, $2 (\cos (-30^{\circ}) +i \sin (-30^{\circ})) = 2(\dfrac{\sqrt 3}{2} -i \dfrac{1}{2} ) \\ = \sqrt 3 -i$
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