What is the inradius of a triangle with sides of 20,21, and 29?

Question

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Help please!

Answer 1

If you mean the radius of the inscribed circle, it is given by

√[(s-a)(s-b)(s-c)/s]

where a, b, and c are the sides of the triangle and s=½(a+b+c)

The formula comes from computing the area of the triangle in two ways: by using Hero's formula, and by dividing the triangle into three smaller triangles and adding their areas. See the source cited below for a derivation.

For this problem. the inradius is 6.