Solve the problem.
-Suppose you would like to cross a 219-foot wide river in a boat. Assume that the boat can travel 38 mph relative to the water and that the current is flowing west at the rate of 7 mph. What bearing
Should be chosen so that the boat will land at a point exactly across from its starting point? Give
Your answer to the nearest tenth of a degree.
A)10.6°
B)7.1°
C)8.5°
D)79.4°

Question

Quizplus · Accepted Answer

The correct answer is A because the boat must travel at an angle upstream so that the current will carry it downstream to the opposite bank. The angle can be found using the formula tan(theta) = opposite/adjacent, where opposite is the width of the river and adjacent is the speed of the boat relative to the water. Plugging in the values, we get tan(theta) = 219/38 = 5.76. Taking the arctangent of both sides, we get theta = 79.4 degrees. However, since the boat is traveling upstream, we need to subtract this angle from 90 degrees to get the bearing, which is 10.6 degrees.

Solve the Problem. -Suppose You Would Like to Cross a 219-Foot Wide River