Algebra and Trigonometry 10th Edition

Published by Cengage Learning
ISBN 10: 9781337271172
ISBN 13: 978-1-33727-117-2

Chapter 8 - 8.2 - Law of Cosines - 8.2 Exercises - Page 573: 9

Answer

a = 18.59 B = $23.79^{o}$ C = $126.21^{o}$

Work Step by Step

Note: The Standard Form of the Law of Cosines is: $a^{2} = b^{2} + c^{2} - 2bc(cosA)$ Note: The Alternative Form of the Law of Cosines is: $cosA = \frac{b^{2} + c^{2} - a^{2}}{2bc}$ To solve the triangle, we need to find a, B, and C. We can use the Standard and Alternative Form of the Law of Cosines to solve the triangle. Finding a: $a^{2} = 15^{2} + 30^{2} - 2(15)(30)cos(30^{o})$ a = 18.59 Finding B: $cosB = \frac{18.59^{2} + 30^{2} - 15^{2}}{2(18.59)(30)}$ B = $23.79^{o}$ Finding C: $cosC = \frac{18.59^{2} + 15^{2} - 30^{2}}{2(18.59)(15)}$ C = $126.21^{o}$ In Total: a = 18.59 B = $23.79^{o}$ C = $126.21^{o}$
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