题目

如图，▱ABCD中，AC=8，BD=6，AD=a，则a的取值范围是． 答案：1＜a＜7 ． 【考点】平行四边形的性质；三角形三边关系． 【分析】由平行四边形的性质得出OA=4，OD=3，再由三角形的三边关系即可得出结果． 【解答】解：如图所示： ∵四边形ABCD是平行四边形， ∴OA=AC=4，OD=BD=3， 在△AOD中，由三角形的三边关系得：4﹣3＜AD＜4+3． 即1＜a＜7； 故答案为：1＜a＜7．Sam, Thank you for asking me to play soccer with you. But I’m afraid I can’t. I have a piano lesson on Tuesday. Maybe another time. NancySandy, Thank you very much for inviting me to your birthday party on Friday. I’d love to come, but I have to go to New York that day. It’s very kind of you. I hope you have a happy birthday party.NancyLucy, Thanks for your invitation. I’d love to go to your house for dinner on Thursday. But I have to get my things ready for travelling. How about coming to my house with Lily? My mother cooks fish very well. I think you’ll like it. I hope to see you before I’m leaving.NancyRose, Would you like to come to my house for dinner tonight? Many of our good friends will come.Nancy1.How many invitations does Nancy get?A. TwoB. ThreeC. FourD. Five2.________ will have a birthday party.A. SamB. SandyC. LucyD. Rose3.Nancy will go to New York on ________.A. TuesdayB. ThursdayC. FridayD. Wednesday4.What does Nancy have to do on Thursday?A. Get her things ready for travelling.B. Cook fish for Lucy and Lily.C. Play soccer with Sam.D. Go to a birthday party.5.Which of the following sentences is TURE?A. Nancy is coming to Rose’s house for dinner.B. Nancy invites Rose to come to her house for dinner.C. Lucy and Lily can’t come to Nancy’s house.D. Sandy is coming to Nancy’s home for dinner.