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January 22, 2017
Posted by **echus** on Monday, October 3, 2011 at 3:26pm.

- geometry -
**Steve**, Monday, October 3, 2011 at 4:10pmHere is a formula in terms of the three sides:

If the sides have length a, b, c, we define the semiperimeter s to be half their sum, so s = (a+b+c)/2. Given this, the radius is given using the following:

rHere is a formula in terms of the three sides:

If the sides have length a, b, c, we define the semiperimeter s to be half their sum, so s = (a+b+c)/2. Given this, the radius is given using the following:

r² = (s - a)*(s - b)*(s - c) / s