Trigonometry 7th Edition

Published by Cengage Learning
ISBN 10: 1111826854
ISBN 13: 978-1-11182-685-7

Chapter 7 - Section 7.2 - The Law of Cosines - 7.2 Problem Set - Page 378: 2

Answer

one-largest

Work Step by Step

If angle $A$ is obtuse ($>90^\circ$), then $B+C <90$ and both of them must be acute. $$a^2 = b^2+c^2-2bc \cos{A}$$ $$ \because \cos{A} \text{ is negative in } QII\\ \therefore a \text{ is the largest side} $$
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