The area of a triangle is 0.5 x base x height
Base of triangle= 10 ft Height of Triangle= 12
Therefore the area of each triangle is 0.5 x 10 X 12= 60 ft^2
The sum of the areas of the triangles = total number of triangles x the surface area of each triangle
Sum of the areas of the trangles= 60 x 4= 240ft^2
Surface area of the square base= base x width
Therefore area of square= 10 x 10 = 100ft^2
Therefore total surface area= 240+100= 340ft^2
