To calculate the area of a triangle with two sides given and the angle opposite the third side, we shall apply the following formula;

The triangle is an isosceles triangle, which mean sides a and b both measure 17.91 ft each and angle C = 21.21 degrees.
Therefore, the area would be;

The correct answer therefore is option C, which is 58.025 sq ft.
This is the closest we got from our calculation which is as a result of approximations