If the diameter of a circle is 20cm, what is the area?

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Answer 1 · 2015-12-31T11:09:38

#"A" = 100pi =314.16# #"cm"^2# #"to 5 significant figures"#

First, observe the formula for calculating the area of a circle:

#"A"=pir^2#

Where:

Since the radius is half of the diameter:

#r=d/2#

#=>20/2#

#=>10#

#:. r^2 = 10^2 = 100#

Returning to our original equation:

#"A" = 100pi =314.16# #"cm"^2# #"to 5"# #"significant figures"#