A square pyramid is called like so because its base is a square.
notice this one, its base is a 0.4x0.4 square, and the triangular faces have a base of 0.4 and an altitude or height of 5.
so we can simply get the area of the base and all four triangular faces and sum them up, and that's the surface area of the pyramid.
![\bf \stackrel{\textit{squarish base}}{(0.4\cdot 0.4)}~~+~~\stackrel{\textit{4 triangles}}{4\left[\cfrac{1}{2}(0.4)(5) \right]}\implies 0.16~~+~~4\implies 4.16](https://tex.z-dn.net/?f=%5Cbf%20%5Cstackrel%7B%5Ctextit%7Bsquarish%20base%7D%7D%7B%280.4%5Ccdot%200.4%29%7D~~%2B~~%5Cstackrel%7B%5Ctextit%7B4%20triangles%7D%7D%7B4%5Cleft%5B%5Ccfrac%7B1%7D%7B2%7D%280.4%29%285%29%20%20%5Cright%5D%7D%5Cimplies%200.16~~%2B~~4%5Cimplies%204.16)
notice this one, its base is a 0.4x0.4 square, and the triangular faces have a base of 0.4 and an altitude or height of 5.
so we can simply get the area of the base and all four triangular faces and sum them up, and that's the surface area of the pyramid.