Lemma t22_24_aux : ~ hypothesis_of_obtuse_saccheri_quadrilaterals -> forall A B0 B00 C0 B C E, ~ Col A B0 C0 -> Perp A C0 B0 C0 -> B0 = B00 -> GradExp2 A B0 B B00 C0 E -> Perp A C0 B C -> Col A C0 C -> Le B0 E B C.