Trigonometry (10th Edition)

Published by Pearson
ISBN 10: 0321671775
ISBN 13: 978-0-32167-177-6

Chapter 8 - Complex Numbers, Polar Equations, and Parametric Equations - Section 8.3 The Product and Quotient Theorems - 8.3 Exercises - Page 369: 5

Answer

$12\sqrt 3+12i$

Work Step by Step

Step 1: $[4(\cos60^{\circ}+i\sin60^{\circ})][6(\cos330^{\circ}+i\sin330^{\circ}]$ Step 2: Using the product theorem, the expression becomes $4(6[\cos(60^{\circ}+330^{\circ})+i\sin(60^{\circ}+330^{\circ})]$ Step 3: Simplifying, $24(\cos390^{\circ}+i\sin390^{\circ})$ Step 4: Since $30^{\circ}$ and $390^{\circ}$ are coterminal angles, the expression becomes $24(\cos30^{\circ}+i\sin30^{\circ})$ Step 5: We know that $\cos30^{\circ}=\frac{\sqrt 3}{2}$ and $\sin30^{\circ}=\frac{1}{2}$ Step 6: Substituting these values in the expression, $24(\frac{\sqrt 3}{2}+\frac{1}{2}i)$ Step 7: Therefore, the final answer is $12\sqrt 3+12i$
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