# Word problem

1. Oct 7, 2008

### yoleven

1. The problem statement, all variables and given/known data
Frank wants to cross a 2.5 km wide river which flows from east to west in a straight path at a rate of 5 km/hr. On the south shore of the river Frank hops in his boat which has a still water speed of 10 km/hr. Frank points the nose of his boat directly north throughout the crossing. How far downstream from his starting point does Frank reach the north shore. How long was the trip

2. Relevant equations

3. The attempt at a solution
I drew a triangle and determined his speed to be 11.18 km/hr
How do i now figure out a triangle that relates to distance when I was dealing with rate?
If the hypotenuse of the rt triangle that I drew was the 11.18 rate of the boat across the river, I can't figure out how to determine the distance down river that he ends up.

2. Oct 7, 2008

### yoleven

Okay, I tried it again. Please tell me if I am totally off.
I had the original right triangle with 11.18 as the hypoteneuse.
I figured the angle there to be 26.5°
Then I said 2.5/cos 26.5°=2.79
Once I had that, Sqrt(2.79^2-2.5^2)=1.24 which is the distance downstream.
Time would be 2.79*11.18=31.192