Asked by Angel
The area of a circle is changing at a rate of 2 in.^(2)/sec. At what rate is its radius changing when the radius is 9 in.?
a. (9/2)in./sec.
b. (2/9)in./sec.
c. (2/9pie)in./sec.
d. (1/9pie)in./sec.
e. (1/9)in./sec.
a. (9/2)in./sec.
b. (2/9)in./sec.
c. (2/9pie)in./sec.
d. (1/9pie)in./sec.
e. (1/9)in./sec.
Answers
Answered by
Reiny
A = πr^2
d(A)/dt = 2πr dr/dt
given: dA/dt = 2
find : dr/dt when r = 9
2 = 2π(9) dr/dt
dr/dt = 1/(9π) inches/sec
d(A)/dt = 2πr dr/dt
given: dA/dt = 2
find : dr/dt when r = 9
2 = 2π(9) dr/dt
dr/dt = 1/(9π) inches/sec