证明：（思路：此题从结论上看实际就是证明点O,A,E,M四点共圆）延长MO交AB于N,连接OA,OB∵AB∥CD,CM=DM∴OM⊥CD,ON⊥AB,AN=BN∴∠AON=∠BON=1/2∠AOB∵∠AEB=1/2∠AOB∴∠AEB=∠AON∴点O,A,E,M四点共圆∴PE·PA=PM·PO请采纳！
