The radius R of the circle inscribed in a triangle with edge lengths A, B, and C is given by the formula

WHERE S=(A+B+C)/2

Define a SCHEME function radius which takes three parameters for the side lengths (perhaps call them A, B, and C) and returns the radius as given by the formula above. (You may use the built-in scheme function sqrt for this purpose. A let construct can save you a lot of typing.)

using dr racket to define a function

R= V(S - A)(S-B)(S C)/S R= V(S - A)(S-B)(S C)/S