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 Circular Fun (Posted on 2005-07-28)
When you draw three circles of radius r such that all three are externally tangent, what is the area of the shape in the center in terms of r?

 See The Solution Submitted by Justin Rating: 3.2857 (7 votes)

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 The solution | Comment 17 of 18 |

When the 3 circles touch each other externally and have the same radius r then on joining their centres we get an equilateral triangle whose sides are 2r. The area of the equilateral triangle is (2(3^1/2)r^2).Since it is an equilateral triangle so all the angles are 60¨¬.So all the sectors have angle 60¨¬ between them and all are equal in area. Therefore the area of the three sectors is       (¥ð(r^2)/6)*3.Therefore the area of the figure is                       (2(3^(1/2))r^2)-(¥ð(r^2)/2).

 Posted by akash on 2005-12-31 12:09:42

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