Suppose you have an isosceles triangle, and each of the equal sides has a length of $1$ foot. Suppose the angle formed by those two sides is $t$. Then the area of the triangle is square feet. Of course, your answer will involve $t$.
Hint: Draw the triangle. Draw the height. It divides the triangle into two congruent right triangles. Compute the missing lengths of the sides of that triangle using the trigonometric functions. Then compute the area of one of those two triangles, and multiply with 2.