19.Use Heron's Formula, that is, the area of a triangle is A= s(-a)(6-b)(8-c), where thetriangle contains sides a, b and c and s=5(a+b+c) to find the area of the triangle with side1lengths: a = 12.4, b = 13.7, c = 20.2.84.9 square units138.4 square units125.2 square units83.3 square units