AP Calculus
posted by Naz on .
The radius of a circle is decreasing at a constant rate of 0.1 centimeters per second. In terms of the circumference C, what is the rate of the area of the circle, in square centimeters per second?
a. (0.2)pie C
b. (0.1)C
c. (0.1)C/2 pie
d. (0.1)^2C
e. (0.1)^2 pie C

C=2πr
A=πr²
dA/dr=2πr=C
dr/dt=0.1 cm/sec
dA/dt
= dA/dr * dr/dt
= 2πr (0.1) cm²/s
= 0.1C cm²/s