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 487: 8

Answer

$\sin\theta=\dfrac{7}{8}$ $\cos\theta=\dfrac{\sqrt{15}}{8}$ $\tan\theta=\dfrac{7\sqrt{15}}{15}$ $\csc\theta=\dfrac{8}{7}$ $\sec\theta=\dfrac{8\sqrt{15}}{15}$ $\cot\theta=\dfrac{\sqrt{15}}{7}$

Work Step by Step

The triangle is shown in the attached image below. Let $c$ be the unknown cathetus of the triangle. Find it using the Pythagorean Theorem: $c=\sqrt{8^{2}-7^{2}}=\sqrt{64-49}=\sqrt{15}$ $\sin\theta=\dfrac{opposite}{hypotenuse}=\dfrac{7}{8}$ $\cos\theta=\dfrac{adjacent}{hypotenuse}=\dfrac{\sqrt{15}}{8}$ $\tan\theta=\dfrac{opposite}{adjacent}=\dfrac{7}{\sqrt{15}}=\dfrac{7\sqrt{15}}{15}$ $\csc\theta=\dfrac{hypotenuse}{opposite}=\dfrac{8}{7}$ $\sec\theta=\dfrac{hypotenuse}{adjacent}=\dfrac{8}{\sqrt{15}}=\dfrac{8\sqrt{15}}{15}$ $\cot\theta=\dfrac{adjacent}{opposite}=\dfrac{\sqrt{15}}{7}$
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