 Similarly, formula_30 and formula_31, so the Conant–Beyer theorem says

which is de Gua's theorem.The generalisation of de Gua's theorem to "n"-simplices with right-angle corners can also be obtained as a special case from the Cayley–Menger determinant formula .Jean Paul de Gua de Malves (1713–85) published the theorem in 1783, but around the same time a slightly more general version was published by another French mathematician, Charles de Tinseau d'Amondans (1746–1818), as well.