To find the surface area using the slant height, we use the formula:
🔎 Proof: The surface area of a square pyramid is the sum of the areas of its square base and four triangular faces:
The area of a triangle is half of the product of its base length (a) and height (l):
Therefore, the area of four triangular faces or the lateral surface area of the square pyramid is:
Thus, the lateral surface area (LSA) of the square pyramid of slant height l is
and the total surface area is