A triangle has a 56-degree angle, formed by a 10-inch side and an x-inch side. Given that the area of the triangle is 18 square inches, find x.
Use the law of cosines to find the length of the third side in terms of x. Then apply Heron's Formula: $\displaystyle A = \sqrt{s(s - a)(s - b)(s - c)}$
where A is the area, s is half of the perimeter, and a, b, and c are the sides. Edit: Chop Suey's method is much easier.