Question

梯形ABCD,AD//BC,AD=4,AB=5,BC=6,AB垂直BC,P是AB上一点,连接PC,PD,PC与PD之和最

Answer 1

∵梯形ABCD是直角梯形,

延长DA到E点,使EA=DA=4,

连接EC,交AB于P点,

这时候的P点能使PC＋PD最小﹙两点之间,线段最短﹚,

∵AD∥BC,

∴△EAP∽△CBP,

∴4／6=AP／﹙5－AP﹚,

∴解得：AP=2.