The area of a circle is 20 square centimeters. What is its circumference?

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Answer 1 · 2017-05-02T01:52:57

#C = 4sqrt(5pi)cm#

Given: #"Area" = 20"cm"^2#

The formula for area of a circle is:

#"Area" = pir^2#

Substitute the given value for the area:

#20"cm"^2 = pir^2#

#r = sqrt(20/pi)"cm" = 2sqrt(5/pi)cm#

The formula for the circumference of a circle is:

#C = 2pir#

Substitute the value for r:

#C = 2pi2sqrt(5/pi)cm#

#C = 4sqrt(5pi)cm#