Vector Angles and Direction

Question

A child walks due east on the deck of a ship at 5 miles per hour. The ship is moving north at a speed of 6 miles per hour.

I was able to solve the speed of the child to the surface of the water to be sqrt(61) mph.

Then to find the angle of the direction from the North (in radians), I tried arctan(6/5) radians, but it says that this is wrong.

Can you explain how to find the angle of the direction from the North?

Answer 1

east at 5 mph as the ship moves north at 6 mph

speed relative to the water = sqr(5^2 +6^2) = sqr61

angle relative to north = 90-arctan(6/5)

= 90-tan^-1(1.2)

= about 90-50.2

= about 39.8 degrees

or in radians

=pi/2 - arctan(1.2)

= about 39.8(pi)/180

= 0.22pi

= about 0.695 radians

also the computer always has some required format where you may have the correct answer, but it's rejected for how you posted it