山东省济南市天桥区2019-2020学年九年级上学期期末考试数学试题

2019—2020学年第一学期九年级期末考试 数 学 试 题 答 案 一、选择题 1. C 2. B 3. B 4. A 5. C 6. D 7. A 8. D 9. D 10. C 11. A 12. D 二、填空题: 13. 增大 ， 14. 6 15. 30 16. 17. 3π 18. ①②③ 三、解答题 19. 原式=1+－1＋2 ··········································································4分 =3 ·································· ·······································6分 20. （1）∵正方形ABCD， ∴∠B=∠C=90°，·································································1分 ∴∠AEB＋∠BAE=90°···························································2分 ∵EF⊥AE， ∴∠AEB＋∠CEF=90°，·························································3分 ∴∠BAE=∠CEF，··································································4分 ∴△ABE∽△ECF； ································································5分 ∴AB：CE＝BE： CF. ·····························································6分 21. 解：作三角形的高AD. 在Rt△ACD中,∠ACD=45°,AC=2, ············································1分 ∴AD=CD=. ····································································3分 在Rt△ABD中,∠B=30°,AD=， ∴BD=，·································································4分 ∴AB=. ··········································································5分 . ∴CB=BD+CD=+·········································································6分 22. 解：设AB的长度为x米，则BC的长度为（32﹣2x）米， 根据题意得：x(32﹣2x)=120， ······································································3分 解得：x1=6，x2=10， ······································································5分 ∴BC＝32﹣2x=20(超过16m舍去)或BC＝32﹣2x=12，····················································7分 答：能，此时BC为12米． ······································································8分 23.画树状图得： 共有12种等可能的结果、、、、、、、、、、、；····························································