A child is in danger of drowning in the river. The river has a current of 2.5 km/hr . The child is 0.6 km from the shore. A rescue boat with speed 20.0 km/hr (with respect to the water) ,located 0.8km downstream, sets off from the shore. What would be the optimum angle (shore -> boat ) to reach the child as fast as possible ? And how long will it take to the boat to reach him? I'm not sure if this is the correct way to draw this : 3. The attempt at a solution a = 0.6 km b = 0.8 km v = 20.0km u = 2.5km c = √(a² + b²) how do I find the angle? I feel a little bit lost, your help is appriciated. Thanks.