Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 6 - Section 6.5 - Complex Numbers in Polar Form; DeMoivre's Theorem - Exercise Set - Page 769: 97

Answer

See the explanation below.

Work Step by Step

The provided complex number $z=r\left( \cos \theta +i\sin \theta \right)$ is in polar form with $r$ and $\theta $ as its modulus and argument respectively. First find the real and imaginary parts of the complex number, which are represented by $a$ and $b$ respectively. $a=r\cos \theta $ and $b=r\sin \theta $ Substitute the value of $r\cos \theta $ and $r\sin \theta $ in the provided complex number. $\begin{align} & z=a+ib \\ & =\left( r\cos \theta \right)+i\left( r\sin \theta \right) \end{align}$ Above is the rectangular form of the assumed complex number. Example: The above explanation can be justified with the help of an example. Let the provided complex number be $z=5\left( \cos 30{}^\circ +i\sin 30{}^\circ \right)$, in polar form. To convert this complex number into rectangular form, just substitute the value of $\cos 30{}^\circ $ and $\sin 30{}^\circ $ in the provided expression. $z=5\left( \frac{\sqrt{3}}{2}+i\frac{1}{2} \right)$ On further simplification $z=\left( \frac{5\sqrt{3}}{2}+\frac{5}{2}i \right)$ The above expression is the rectangular form of the provided expression.
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.