Question

How do I find the surface area tetrahedron? I forgot the formula

Answer 1

The surface area of the tetrahedron is simply four times the area of a single equilateral triangle face:
$A=\frac{1}{4}\sqrt{3} *a^2$

The tetrahedron has 4 equal triangle faces, so the total surface formula is:
$S=4A= \sqrt{3}*a^2$, where $a$ represents length of triangle's side.