1. Prove that every Saccheri quadrilateral has the properties listed in Theorem 4.8.10. 2. Prove the

1. Prove that every Saccheri quadrilateral has the properties listed in Theorem 4.8.10. 2. Prove the following result: If and m are two lines and there exist three distinct points P, Q, and R on m such that dP ,  D dQ,  D dR, , then either m D  or m  .