If a circle has area 81π square inches, what is the radius?

1 Answer
Don't Memorise
Jul 31, 2015

#r=color(green)(9# inches.

Explanation:

The formula for area of a circle is
#color(green)(pir^2#
Where
#r# denotes the radius of the circle.

Equating the formula for area with the area of the circle provided.

#color(green)(cancelpir^2) = 81cancelpi#

#r^2=81#

#r=sqrt81#

#r=color(green)(9# inches.

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