Nice to meet you. My name is Sally Simpson. Sally is my first name. Simpson is my last name. I'm in Huangzhou, China now. I'm a student in HZFL Middle School. My classroom is very nice. My telephone number is 832—4895.
Good morning! I'm Wu Lei. My first name is Lei and my last name is Wu. I'm in Macheng now. I'm a student in HY Middle School. My phone number is 291—5638. And my QQ number is 83250194.
Hi! My name is Dong Huixia. I'm an English teacher in JM Middle School, Huangmei. I like (喜欢) my students. I'm their good friend. My telephone number is 338—0479.
Hello! My name is Mike Brown. I'm in Wuxue, China now. I'm a student in SY Middle School. My telephone number is 625—1899. And my QQ number is 389410663. My parents are in the school, too.
如图，AB是⊙O的直径，点C是⊙O上一点，AD和过点C的切线互相垂直，垂足为D，直线DC与AB的延长线相交于P．弦CE平分∠ACB，交直径AB于点F，连结BE．
（1）求证：AC平分∠DAB；
（2）探究线段PC，PF之间的大小关系，并加以证明；
（3）若tan∠PCB=34，BE=52，求PF的长．
