In order to get the area of a triangle using sides, the formula that we are going to use is Heron's formula. This is after from "Hero of Alexandria". So here is the step by step process: First, we calculate for s (half of the triangles perimeter) s = a+b+c divided by 2. s = 6 + 10 + 12 / 2 s =28/2 s = 14 Now that we have the s, we can now calculate for the area. A = square root of s(s-a)(s-b)(s-c) A= square root of 14 x 8 x 4 x 2 A= square root of 896 A = 29.93 The area of triangle DEF is 29.93 square feet or 30 square feet. Hope this answer helps.