so, the base has legths of 2, and a surface area of 16
ok... hmm well, the pyramid, notice the picture below, has 4 triangular faces and one squarish base/bottom, we know the lengths of the base are 2 each, so the area of the base is 2x2, or 4
if we subtract the area of the base from those total of 16, we get 16 - 4 = 12, meaning, the 4 triangular faces will have to evenly share those 12 units fo their area
4 triangles, 12/4, so that means each gets an areas of 3units
if you notice in the picture, the slant-height of the pyramid, is the "altitude" or height of the triangular face
so... hmm just solve for "h"