Question

Miguel is driving his motorboat across a river. The speed of the boat in still water is 10 mi/h. The river flows directly south at 3 mi/h. If Miguel heads directly west, what are the boat’s resultant speed and direction? Round answers to the nearest tenth.

Answer 1

you have a right triangle with legs 3 and 10.

The resultant speed is the hypotenuse: √(36+100) = √136 = 11.7

direction is W θ S

where tanθ = 3/10, so that's W16.7°S

Answer 2

the resultant speed is the hypotenuse
9+100=109
√109=10.4