Calculating River Velocity with Relative Boat Motion

[astrokat11]

In order to get across a river that's 300m wide at a distance 130m upstream, a boat must angle at 40degrees. The velocity of the boat in still water is 2.2m/s. What is the velocity of the river?

Thanks for the help!
AstroKat

 

[vanesch]

You should show some work before we help you...

 

[astrokat11]

river/boat velocity problem

Ok, so what I have so far is that this might be a relative velocity problem. I know the velocity of the boat relative to the Earth is 2.2m/s. I also know that if he aims upstream 40 degrees in still water, he will go further than 130 m. I'm just not really even sure where to start with this problem! Can someone lead me in the right direction and then I'll work on it more? I've been thinking about this problem for 4 days now and I'm having a lot of trouble with (I'm sure) a simple problem.
Thanks