Asked by Gary
Let A be the area of a circle with radius r that is increasing in size with respect to time. If the rate of change of the area is 8 cm/s, find the rate of change of the radius when the radius is 3 cm.
Answers
Answered by
Steve
ah, a nice related-rates problem.
a = pi r^2
da/dt = 2pi r dr/dt
when r=3,
8 = 2pi(3)(dr/dt)
dr/dt = 4/(3pi) cm/s
By the way, da/dt is 8 cm^2/s. That makes the units come out right.
cm^2/s = 2pi(cm)(cm/s)
a = pi r^2
da/dt = 2pi r dr/dt
when r=3,
8 = 2pi(3)(dr/dt)
dr/dt = 4/(3pi) cm/s
By the way, da/dt is 8 cm^2/s. That makes the units come out right.
cm^2/s = 2pi(cm)(cm/s)
There are no AI answers yet. The ability to request AI answers is coming soon!
Submit Your Answer
We prioritize human answers over AI answers.
If you are human, and you can answer this question, please submit your answer.