The area of the triangle with vertices (a, b+ c), (b, c + a) and (c, a + b) is
0
1
a + b + c
a2 + b2 + c2
Area of the triangle = 12[x1(y2 - y3) + x2 (y3 - y1)+ x3(y1 - y2)]
So, 12[a(c+a-a-b) + b(a+b-b-c) + c(b+c-c-a)
= 12[ ac - ab + ab - bc + bc - ac]
= 0