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: 22

Answer

The measurement of side ‘a’ is \[\text{54 cm}\], measurement of side ‘b’ is\[\text{67 cm}\] and the measurement of angle B is \[51{}^\circ \].

Work Step by Step

Substitute the values in the above function as follows: \[\begin{align} & \text{sin 39}{}^\circ =\frac{a}{86} \\ & a=\text{sin 39}{}^\circ \times 86 \\ & =0.629\times 86 \\ & \approx 54 \end{align}\] It implies that: \[a\approx 54\text{ cm}\] Now, in order to compute the value of c, use the trigonometric ratio of cos A as follows: \[\text{cos }A=\frac{\text{Side adjacent to angle }A}{\text{Hypotenuse}}\] Substitute the values in the above function as follows: \[\begin{align} & \text{cos 39}{}^\circ =\frac{b}{86} \\ & b=\text{cos 39}{}^\circ \times 86 \\ & =0.776\times 86 \\ & \approx 67 \end{align}\] It implies that: \[b\approx 67\text{ cm}\] 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, \[\begin{align} & m\measuredangle A+m\measuredangle B+m\measuredangle C=180{}^\circ \\ & 39{}^\circ +m\measuredangle B+90{}^\circ =180{}^\circ \\ & m\measuredangle B=180{}^\circ -90{}^\circ -39{}^\circ \\ & =51{}^\circ \end{align}\] It implies that: \[\measuredangle B=51{}^\circ \] Hence, the measurement of side denoted by ‘a’ is \[54\text{ cm}\], measurement of side denoted by ‘b’ is\[67\text{ cm}\] and the measurement of angle B is \[51{}^\circ \].
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.