A circular pen has an area of #64pi# square yards. What is the circumference of the pen?

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Answer 1 · 2018-01-23T03:15:27

#16pi#

To find the circumference of a circle, you need the radius.

Remember that the area of a circle is #A=pir^2#

Since we know the area, we can plug it in for #A#

#64pi=pir^2#
#64cancelpi=cancelpir^2#
#64=r^2#

Take the square root of both sides to find the radius:

#r=8#

Now, use the circumference formula of #2pir#

#C=2pi(8)#

This simplifies to the circumference equalling #16pi#