Lola G.

asked • 06/21/20

Area of a circle

Let A be the area of a circle with radius, r. If  dr/dt=4, find dA/dt when r=4 .

1 Expert Answer

By:

Doug C. answered • 06/21/20

Tutor
5.0 (1,553)

Math Tutor with Reputation to make difficult concepts understandable

See tutors like this
See tutors like this

The formula for the area of a circle is A=¨πr2.


Taking the derivative with respect to t, gives dA/dt = 2πr dr/dt.


So dA/dt = 2π(4)(4) = 32π sq units per unit of time. That is how fast the area is changing when r = 4 (and dr/dt = 4).

Upvote • 0 Downvote
More
Report

Still looking for help? Get the right answer, fast.

Ask a question for free

Get a free answer to a quick problem.
Most questions answered within 4 hours.

OR

Find an Online Tutor Now

Choose an expert and meet online. No packages or subscriptions, pay only for the time you need.