A river flows due south at 1.4 mi/h. In what direction should the swimmer head, at a velocity of 4 mi/h, in order to arrive at a landing point due east of his starting point?

Question

A river flows due south at 1.4 mi/h. In what direction should the swimmer head, at a velocity of 4 mi/h, in order to arrive at a landing point due east of his starting point? (Round your answer to one decimal place.)

Answer 1

Let θ is NθE bearing of swimmer heading. Then 4cosθ = 1.4; θ = cos^-1(1.4/4) = 69.5°