math
posted by Ann .
a boat crosses a river and arrives at a point on the opposite bank directly across from its starting position. The boat traveks at 4m/s and the current is 2m/s. If the river is 600 m wide in what direction must the boat steer and how long will it take to cross?

current toward y
We want to go in +x direction
steer at angle T up from x axis
components toward x
Vx = 4 cos T
components toward y
Vy = 4 sin T  2
we want Vy = 0
so
2 = 4 sin T
sin T = 1/2
T = 30 degrees or in compass heading
30 degrees North of East = 60 degrees true