# Math Help - vector prob

1. ## vector prob

A child walks due east on the deck of a ship at 1 miles per hour.
The ship is moving north at a speed of 10 miles per hour.

Find the speed and direction of the child relative to the surface of the water.
i was able to find the speed: sqrt(10^2+1^2) = 10.05

need help finding "The angle of the direction from the north" in radians

2. Originally Posted by viet
i was able to find the speed: sqrt(10^2+1^2) = 10.05

need help finding "The angle of the direction from the north" in radians
Do you see why the angle from EAST is $\arctan \frac{10}{1}$? The angle from NORTH is 90 degrees minus the angle from EAST.