题目

如图17,已知△ABC是⊙O的内接三角形,PA是切线,PB交AC于E点,交⊙O于D点,且PE =PA,∠ABC=60°,PD=1,BD =8,则CE的长为( )图17A.                     B.9                    C.                    D.4 答案：思路解析:由弦切角定理得∠PAE =∠ABC =60°,又∵PE =PA,∴△PAE为等边三角形.由切割线定理得PA2=PD·PB,求得PA =3=AE =PE,∴DE =PE-PD=3-1=2;BE =BD -DE =8-2 =6.由相交弦定理得BE·ED =AE·EC.∴ = =4.答案:D将所给单词连成完整、正确的句子。（请注意各题的变化）（1）you, are, the, play, guitar（?）（2）from, Marco Polo, be, a, man, Italy（.）（3）you, ready, project, are, for, you（?）（4）learn, want, she, to, dance, to（.）（5）house, last, own, his, have, month, he（.）