Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 10 - Geometry - 10.6 Right Triangle Trigonometry - Exercise Set 10.6 - Page 665: 8

Answer

Value of \[\sin A=\frac{24}{25}\], \[\cos A=\frac{7}{25}\], and \[\tan A=\frac{24}{7}\].

Work Step by Step

The length of hypotenuse that is \[\left( c=25 \right)\], the side opposite to acute angle A that is \[\left( a=24 \right)\]. First, it is required to compute side adjacent to acute angle A, that is b, using the Pythagorean Theorem. Compute the side adjacent to acute angle A; that is b of a triangle, by the formula as follows: \[\begin{align} & c\text{ }=\sqrt{{{a}^{2}}+{{b}^{2}}} \\ & 25=\sqrt{{{24}^{2}}+{{b}^{2}}} \\ & {{25}^{2}}={{24}^{2}}+{{b}^{2}} \\ & 625=576+{{b}^{2}} \end{align}\] Further it can be simplified as: \[\begin{align} & {{b}^{2}}=625-576 \\ & {{b}^{2}}=49 \end{align}\] Take square root both the sides as follows: \[\begin{align} & \sqrt{{{b}^{2}}}=\sqrt{49} \\ & \text{b}=7 \end{align}\] Now, compute the different trigonometric ratios using the formulas: \[\begin{align} & \sin A=\frac{\text{Side opposite to angle }A}{\text{Hypotenuse}} \\ & =\frac{24}{25} \end{align}\] Therefore, \[\sin A=\frac{24}{25}\] \[\begin{align} & \cos \text{ }A=\frac{\text{Side adjacent to angle }A}{\text{Hypotenuse}} \\ & =\frac{7}{25} \end{align}\] Therefore, \[\cos A=\frac{7}{25}\] \[\begin{align} & \text{tan }A=\frac{\text{Side opposite angle A}}{\text{Side adjacent to angle A}} \\ & =\frac{24}{7} \end{align}\] Therefore, \[\tan A=\frac{24}{7}\] Hence, the value of trigonometric ratios is, \[\sin A=\frac{24}{25}\], \[\cos A=\frac{7}{25}\], and \[\tan A=\frac{24}{7}\].
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