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 666: 19

Answer

The measurement of side ‘a’ is \[18\text{ yd}\], measurement of side ‘c’ is\[29\text{ yd}\] and the measurement of angle B is \[50{}^\circ \].

Work Step by Step

Substitute the values in the above formula as mentioned below: \[\begin{align} & \text{tan 40}{}^\circ =\frac{a}{22} \\ & a=\text{tan 40}{}^\circ \times 22 \\ & =0.8395\times 22 \\ & =18.4707 \end{align}\] It implies that: \[a\approx 18\text{ yd}\] Now, in order to compute the value of c, use the trigonometric ratio of cos A as follows: \[\cos A=\frac{\text{Side adjacent to angle }A}{\text{Hypotenuse}}\] Substitute the values in the above formula as follows: \[\begin{align} & \cos \text{40}{}^\circ =\frac{22}{c} \\ & c=\frac{22}{\cos \text{40}{}^\circ } \\ & =\frac{22}{0.7658} \\ & =29 \end{align}\] It implies that: \[c\approx 29\text{ yd}\] Now, compute the third missing angle using angle sum property which specifies that sum of all angles of a triangle is equal to 180 degree. Accordingly, \[\begin{align} & m\measuredangle A+m\measuredangle B+m\measuredangle C=180{}^\circ \\ & 40{}^\circ +m\measuredangle B+90{}^\circ =180{}^\circ \\ & m\measuredangle B=180{}^\circ -90{}^\circ -40{}^\circ \\ & =50{}^\circ \end{align}\] It implies that: \[\measuredangle B=50{}^\circ \] Hence, the measurement of side denoted by ‘a’ is \[18\text{ yd}\], measurement of side denoted by ‘c’ is\[29\text{ yd}\] and the measurement of angle B is \[50{}^\circ \].
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