Chapter 6, Problem 7PP

(Numerical) Heron’s formula for the area, A, of a triangle with sides of length a, b, and c is

$A=\sqrt{s(s-a)(s-b)(s-c)}$

where

$s=\frac{(a+b+c)}{2}$

Write, test, and execute a function that accepts the values of a, b, and c as parameters from a calling function, and then calculates the values of $sand\left[s\left(s-a\right)\left(s-b\right)\left(s-c\right)\right].$ If this quantity is positive, the function calculates A. If the quantity is negative, a, b, and c do not form a triangle, and the function should set $A=-1.$ The value of A should be returned by the function.