Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Published by Pearson
ISBN 10: 0-32193-104-1
ISBN 13: 978-0-32193-104-7

Chapter 7 - Applications of Trigonometric Functions - Section 7.3 The Law of Cosines - 7.3 Assess Your Understanding - Page 559: 39

Answer

two triangles. $B_1 \approx35.4^\circ$ $C_1\approx134.6^\circ$ $c_1 \approx12.29$, $B_2\approx144.6^\circ$, $C_2\approx25.4^\circ$ $c_2 \approx7.40$

Work Step by Step

1. Use the Law of Sines, we have $\frac{3}{sin10^\circ}=\frac{10}{sinB}=\frac{c}{sinC}$, thus $B_1=sin^{-1}(\frac{10sin10^\circ}{3})\approx35.4^\circ$ or $B_2\approx144.6^\circ$, two triangles. 2. Find the third angle $C_1\approx(180-10-35.4)=134.6^\circ$ or $C_2\approx(180-10-144.6)=25.4^\circ$ 3. thus $c_1=\frac{3sin134.6^\circ}{sin10^\circ}\approx12.29$, $c_2=\frac{3sin25.4^\circ}{sin10^\circ}\approx7.40$
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