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 9 - Analytic Geometry - Section 9.5 Rotation of Axes; General Form of a Conic - 9.5 Assess Your Understanding - Page 699: 61

Answer

$A \approx39.4^\circ$, $B \approx54.7^\circ$, $C \approx85.9^\circ$.

Work Step by Step

1. Use the Law of Cosines, we have $A=cos^{-1}(\frac{11^2+9^2-7^2}{2(11)(9)})\approx39.4^\circ$, 2. Use the Law of Cosines, we have $B=cos^{-1}(\frac{11^2+7^2-9^2}{2(11)(7)})\approx54.7^\circ$, 3. Find the third angle $C=180-A-B\approx85.9^\circ$.
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