Question

A regular tetrahedron is a three dimensional object that has four faces, each of which is an equilateral triangle. each of the of the edges of such an object has a length l. the height h of a regular tetrahedron is the perpendicular distance from one corner to the center of the opposite triangular face. show that the ratio h/l = sqrt (2/3).

So far I have h/l = sqrt(3)/2