When were the boats closest to each other?

[zapped]

Homework Statement

A boat leave a dock at noon and heads weat at a speed 25km/h. Another boat heads north at 20km/h and reaches the same dock at 1:00 pm. when were the boats closest to each other?

Homework Equations

when were the boats closest to each other?

The Attempt at a Solution

I use the pythagorean for the distance
but I'm not sure about how to sub them in?
I tried to assume that the second boat also leaves at noon, so the total distance will be 20km. But that's wrong. Please help, thanks =P

 

[razored]

First, I think you have to find the rate of change of the hypotenuse.

 

[tiny-tim]

Hi zapped!

A boat leave a dock at noon and heads weat at a speed 25km/h. Another boat heads north at 20km/h and reaches the same dock at 1:00 pm. when were the boats closest to each other?
…
I use the pythagorean for the distance
but I'm not sure about how to sub them in?
I tried to assume that the second boat also leaves at noon, so the total distance will be 20km. But that's wrong.

No, that assumption is fine (not necessary, but fine).

Anyway, minimising the pythagorean, which is what you tried to do, should have worked …

show us what you got for the pythagorean