A rectangular base, and an apex directly above its centre. The same three numbers describe all of it. Whatever you choose stays with you for the whole page: every face, every net, every slant from here on is yours, not ours.
Make the base square for a right square pyramid, then flatten the height right down and watch the slant faces fall towards the base. Come back to this slider at any point — nothing on this page is locked to one set of numbers.