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: 20

Answer

The measurement of side ‘a’ is \[\text{74 yd}\], measurement of side ‘c’ is\[\text{88 yd}\] and the measurement of angle B is \[33{}^\circ \].

Work Step by Step

Substitute the values in the above formula as mentioned below: \[\begin{align} & \text{tan 57}{}^\circ =\frac{a}{48} \\ & a=\text{tan 57}{}^\circ \times 48 \\ & =1.5412\times 48 \\ & \approx 74 \end{align}\] It implies that: \[a\approx 74\text{ yd}\] Now, in order to compute the value of c, use the trigonometric ratio of cos A as follows: \[\cos \text{ }A=\frac{\text{Side adjacent to angle }A}{\text{Hypotenuse}}\] \[\begin{align} & \cos \text{57}{}^\circ =\frac{48}{c} \\ & c=\frac{48}{\cos \text{ 57}{}^\circ } \\ & =\frac{48}{0.5443} \\ & \approx 88 \end{align}\] It implies that: \[c\approx 88\text{ yd}\] 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, \[\begin{align} & m\measuredangle A+m\measuredangle B+m\measuredangle C=180{}^\circ \\ & 57{}^\circ +m\measuredangle B+90{}^\circ =180{}^\circ \\ & m\measuredangle B=180{}^\circ -90{}^\circ -57{}^\circ \\ & =33{}^\circ \end{align}\] It implies that: \[\measuredangle B=33{}^\circ \] Hence, the measurement of side denoted by ‘a’ is \[74\text{ yd}\], measurement of side denoted by ‘c’ is\[88\text{ yd}\] and the measurement of angle B is \[33{}^\circ \].
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