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:

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