Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 6 - Section 6.2 - Trigonometry of Right Triangles - 6.2 Exercises - Page 488: 40

Answer

$\angle A=22^{\circ}$ $a\approx374.62$ $;$ $b\approx927.18$

Work Step by Step

The triangle is shown in the attached image below. Two angles are known. Let $\angle A$ be the unknown angle, $\angle B$ be the known $68^{\circ}$ angle and $\angle C$ be the right angle. Since $\angle A+\angle B+\angle C=180^{\circ}$, substitute the known angles into the formula and solve for $\angle A$: $\angle A=180^{\circ}-90^{\circ}-68^{\circ}=22^{\circ}$ Use the sine trigonometric ratio of the angle marked as $68^{\circ}$ to find the cathetus marked as $b$: $\sin68^{\circ}=\dfrac{b}{1000}$ $b=1000\sin68^{\circ}\approx927.18$ Use the Pythagorean Theorem to find the other cathetus: $a=\sqrt{1000^{2}-927.18^{2}}\approx374.62$
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