Question 126
A regular tetrahedron has a square shadow of area $16$ when projected onto a flat surface (light is shone perpendicular onto the plane). Compute the sidelength of the regular tetrahedron.
(For example, the shadow of a sphere with radius $1$ onto a flat surface is a disk of radius $1$.)
(For example, the shadow of a sphere with radius $1$ onto a flat surface is a disk of radius $1$.)