Chapter 4.3, Problem 66E

To determine

Find the width of the river.

Answer to Problem 66E

Width of the river is 137.638 meter.

Explanation of Solution

Given:

Width of river=W

Distance between instrument and biologist=100 meter

Angle made by biologist and other end of river $\theta =54°$

Using right angle triangle identity

  $\tan \theta =\frac{\text{opposite arm of}\theta }{\text{adject arm of}\theta }$

  $\tan {54}^{\circ }=\frac{\text{W}}{100}$

  $\text{W}=100\tan {54}^{\circ }$

Put the value of $\tan {54}^{\circ }=1.37638$

  $W=100\times 1.37638$

W=137.638 meter

Width of the river is 137.638 meter.