related rates

[racuna]

A man starts walking north at 4ft./s from a point P. 5 minutes later a woman starts walking south at 5ft./s from a point 500ft due east of P. At what rate are the people moving apart 15 minutes after the woman starts walking?


I don't know how to start help.

 

[tkhunny]

A man starts walking north at 4ft./s from a point P. 5 minutes later a woman starts walking south at 5ft./s from a point 500ft due east of P. At what rate are the people moving apart 15 minutes after the woman starts walking?

Draw a picture. Connect things up with vertical and horizontal line segments. (The horizontal part will be 500 ft.) There's a Pythagorean Theorem in there, somewhere. Let's see what you get.