pyramid=4 triangles and 1 square base
area of triangle=(1/2)bh
4 triangles
therefor
area of 4 triangles=4(1/2)bh=
area of 4 triangles=area of faces of pyramid
area of faces of pyramid=4/2bh
area of faces of pyramid=2bh
h=slant height
2bh is answer where h=slant height and b=base legnth