题目

of the students are going to visit the factory next week. A . Three fifth B . Third fifths C . Three fives D . Three fifths 答案：D如图，AB、CD是半径为5的⊙O的两条弦，AB=8，CD=6，MN是直径，AB⊥MN于点E，CD⊥MN于点F，P为EF上的任意一点，则PA+PC的最小值为    ．