Heron's Formula relates the lengths of the sides of a triangle to the area of the triangle. The formula is A=\sqrt{s(s-a)(s-b)(s-c)} , where s is the semiperimeter, or one half the perimeter, of the triangle and a,b, and c are the side lengths.
a. Use Heron's Formula to find the area of a triangle with side lengths 7, 10, and 4.