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: 28

Answer

The measure of length x is \[50\text{ units}\].

Work Step by Step

The trigonometric ratio for \[\text{Tangent }A\] will be determined by dividing the opposite side of angle A with the adjacent side of the triangle. To determine the length of x, first compute the length of BC using the equation as shown below: In\[\vartriangle ABC\], we have \[\begin{align} & \text{Tangent }A=\frac{\text{Opposite side of angle }A}{\text{Adjacent side of angle }A} \\ & =\frac{BC}{AC} \\ & \text{Tangent 20}{}^\circ =\frac{BC}{100} \end{align}\] \[\begin{align} & BC=\text{Tangent 20}{}^\circ \times 100 \\ & =0.3641\times 100 \\ & =36.41 \end{align}\] Now, compute the length of the \[CD\] using the equation as shown below: In\[\vartriangle ACD\], we have \[\begin{align} & \text{Tangent }A=\frac{\text{Opposite side of angle }A}{\text{Adjacent side of angle }A} \\ & =\frac{CD}{AC} \\ & \text{Tangent 8}{}^\circ =\frac{CD}{100} \end{align}\] \[\begin{align} & CD=\text{Tangent 8}{}^\circ \times 100 \\ & =0.1405\times 100 \\ & =14 \end{align}\] Now, as per the given figure \[\begin{align} & x=BD \\ & =BC+CD \\ & =36+14 \\ & =50 \end{align}\] Hence, the measure of length x is \[50\text{ units}\].
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