Area of base = 10 x 10 = 100 ft^2As angle is 45 degree, height of the side triangle = 10/2 = 5 ftArea of a side triangle = 1/2 x 10 x 5 = 25 ft^2Surface area of the square pyramid= Area of base + total area of the four sides= 100 ft^2 + 4 x 25 ft^2= 200 ft^2