Prove that the base of a Saccheri Quadrilateral in absolute geometry has length less '...

Prove that the base of a Saccheri Quadrilateral in absolute geometry has length less ' than or equal to that of the summit. (Hint: Show that m∠ 1 + m∠2 = 90 ≤ m∠2 + m∠3, which implies that m∠ 1 ≥ m ∠ 3; apply the Hinge Theorem in Section 3.5 to ∆CAD and ∆ACB.)