A square pyramid has a base area of 25 ft2. The pyramid's total surface area is 105 ft2.

What is the area of each triangular face?

Square root of 25=5. 105 times 5=525

525=the area of each triangular face.

The total surface area (105 ft2) minus the base areas (25 ft2) = 80 ft2. So, the total area of all the triangular faces must = 80 ft2. In a square pyramid, there are four triangular faces, so you take the total area of all the triangular faces and divide that by the four faces to get the area for each triangular face: 80 : 4 = 20 ft2.