Answer:
We know that total surface area is the area of of the base + area of all the walls + area of the top
here we are working with a pyramid whose base is a square but the wall are four triangles
as triangles are connected on the top , there would be no top area ( as the top would be a point ( where all four triangles are being join )
so total area is = area of base + area of four walls ( triangles here )
Explanation: