Question

A triangle has sides with lengths of 8, 4, and 7. What is the radius of the triangles inscribed circle?

Answer 1

r = `\sqrt{3135}/38`

About 1.47.

Explanation:

Let s be half the perimeter of the triancle with sides a, b, c. Then the radius of the inscribed circle is given by:

r=`\sqrt{(s-a)(s-b)(s-c)/s}`

See here:

http://www.efunda.com/math/areas/circleinscribetrianglegen.cfm