Distance & Time - Extreme Value Problems

[Ryan2005]

A boat leaves a dock at noon and head west at a speed of 25km/h. Another boat heads north at 20km/h and reaches the same dock at 1:00 p.m. When were teh boats closest to each other?

 

[Gene]

Boat A is at x = 25t
Boat B is at y = 20(t-1)
The distance between them is
S = sqrt(x^2+y^2)
Solve for dS/dt = 0

 

[Ryan2005]

Thanx for ur help