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MartinBrits
Feb 10, 2015, 10:53 AM
An oil spill on the open sea in calm weather spreads in a circular pattern. If the radius of the oil spill increases at the rate of 0.9m/s, how fast is the area of the spill increasing when its radius is 225?

ebaines
Feb 10, 2015, 10:56 AM
You do know the formula for the area of a circle, right? You're looking to take its derivative with respect to time - try it and post back with what you get.

MartinBrits
Feb 11, 2015, 09:52 AM
@ EBAINES.Please verify my method below.A=πrēdr/dt = 0.9m/sr = 225mdA/dt = 2πr(dr/dt)dA/dt = 2π(225)(0.9)dA/dt = 1272mē/sThanks in advance

@ EBAINES


A=πrē
dr/dt = 0.9m/s
r = 225m


dA/dt = 2πr(dr/dt)
dA/dt = 2π(225)(0.9)
dA/dt = 1272mē/s


Thanks in advance

ebaines
Feb 11, 2015, 11:34 AM
dA/dt = 1272mē/s


Correct!