If A is the area of a circle with radius r and the circle expands as time passes, find

dA

dt

in terms of

dr

dt

$.$

dA

dt

$=$

Correct: Your answer is correct.

dr

dt

$($b$)$

Suppose oil spills from a ruptured tanker and spreads in a circular pattern. If the radius of the oil spill increases at a constant rate of $2$ m$/$s$,$ exactly how fast $($in m$2/$s$)$ is the area of the spill increasing when the radius is

$25$ m$?$