SOLUTION: if the radius of a circle is increased 100% , the area of the circle is increased ( 400% ) how did we get that answer ?? thank you ..

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Question 1055761: if the radius of a circle is increased 100% , the area of the circle is increased ( 400% )
how did we get that answer ??
thank you ..
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
A is original area and 4A is the new area.
system%28A=pi%2Ar%5E2%2C4A=pi%282r%29%5E2%29

Calculating for the new area,
4A=pi%2A4%2Ar%5E2
4A%281%2F4%29=%281%2F4%294%2Api%2Ar%5E2
A=pi%2Ar%5E2