Question

A man wishes to row the shortest possible distance from north to south across a river which is flowing at 2 km/hr from the east. He can row at 4 km/hr. (a) In which direction should he steer

Answer 1

From the diagram we have that

$sin\theta = \frac{2}{4}$

$\theta = sin^{-1} (\frac{1}{2})$

$\theta = 30\°$

Therefore the direction is 30° from east of south