When creating the formula for surface area of a triangular pyramid (SA= 1/2ab + 3(1/2lb)), what formula is being used?

volume
area of a square
area of a triangle
perimeter

The formula being used is for the surface area of a triangular pyramid.

The formula being used is the formula for surface area, specifically for a triangular pyramid.

just choose one of the four

The formula being used is for the surface area.

Choose on of these below

volume
area of a square
area of a triangle
perimeter