An isosceles triangle has a vertex angle of 26°. Two sides of the triangle are each 15 ft long. Find the area of the triangle.

check the picture below.

an isosceles triangle has two twin sides, coming out of the "vertex", the angles made by the twin sides make two twin angles on the base, like in the picture, since the angles are twins, that means each one is half of 180 - 26, or just 77°.

make sure your calculator is in Degree mode.