Posted by T.Gracken on October 20, 2002 at 09:39:38:
In Reply to: need help with related rates~ posted by supi on October 20, 2002 at 01:35:06:
: A man starts walking north at 4 ft/s from a point P. Five minutes later a woman starts walking south at 5 ft/s from a point 500 ft due east of P. At what rate are th people moving apart 15 min after the woman starts walking?
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DRAW A DIAGRAM of what's happening (birds eye view so to speak).
notice there is a right triangle
label sides using variables
use pythagorean theorem to write the relationship of sides length at given time.
differentiate
substitute