The radius of a circle is constantly increasing. At a certain moment, the rate of increase of the circumference is the same as the rate of increase of the area. At that moment, what is the area of the circle?
a. 1/pi
b.pi/4
c.4pi
d.pi
e.4/pi
rate of change circumference=rate of change area, derivative of circumference(2piR)=derivative of area(piR^2), 2pi=2piR, R=1, plug back into area formula: piR^2, pi(1)^2, area=pi :)
