The area of an arbitrary triangle can be computed using the formula


		Area = sqrt(s*(s-a)*(s-b)*(s-c))

where a,b,c are the lengths of the 3 sides, and s is the semiperimeter,

		s = (a + b + c)/2

Write a function that uses five parameters: three value parameters
that provide the lengths of the edges, and two reference parameters
that compute the area and perimeter (not the semiperimeter). Make the
function robust, in the sense that it should produce correct results
for legal triangles and reasonable results when the sides don't
produce a triangle.