The speed of the water flow in the river is 4 meters per second. The boat floats perpendicular to the current

The speed of the water flow in the river is 4 meters per second. The boat floats perpendicular to the current at a speed of 3 meters per second relative to the water. Determine the boat speed relative to the shore.

1. The vector of the speed of the water flow in the river and the vector of the boat’s speed are perpendicular to each other and form between themselves a right-angled triangle with a hypotenuse, which is the vector of the speed relative to the coast. Therefore, the square of the boat speed relative to the shore is:
v ^ 2 = 4 ^ 2 + 3 ^ 2 = 16 + 9 = 25;
v = 5;
2. Answer: 5 m / s.