Question

If a captain wants to take her boat (speed in still water: 5.0m/s) directly across a river with a current of 3.5m/s, what upstream angle should she head at?

Answer 1

Let's make a diagram to visualize the problem.

To find the angle, we have to use the tangent trigonometric reason, which is the ratio between the opposite leg and the adjacent leg.

$\tan \alpha=\frac{3.5}{5}\to\alpha=\tan ^{-1}(\frac{3.5}{5})\to\alpha\approx35$

Therefore, the angle sould be 35 degrees.