山东省济南市槐荫区2020-2021学年九年级上学期期末考试数学试题（可编辑PDF版）

$$ $$ 数学第 1 页(共 8 页) 九年级数学试题参考答案与评分标准 一、选择题 题号 1 2 3 4 5 6 7 8 9 10 11 12 答案 C C B B B A B A D D C A 二、填空题 13. 5 14. 2 2 15. 6 16. 3 4 17. (2，－4) 18. 2 3 －2 三、解答题 19. 解：2cos45°－ 3 2 tan30°cos30°+sin 2 60° =2× 2 2 － 3 2 × 3 3 × 3 2 + 23 ( ) 2 ················································· 4 分 = 2 － 3 4 + 3 4 ··········································································· 5 分 = 2 ······················································································· 6 分 20.解：(1)3 ······················································································ 2 分 (2)如图所示，△ A1B1C1 即为所求．（画图 3 分，结论 1 分） ······································································································ 6 分 数学第 2 页(共 8 页) 21.解： 证明：∵AB＝6，BD＝2， ∴AD＝4， ························································································ 1 分 ∵AC＝8，CE＝5， ∴AE＝3， ························································································ 2 分 ∴ 2 1 6 3  AB AE ， 2 1 8 4  AC AD ， ····························································· 3 分 ∴ AC AD AB AE  ， ·················································································· 4 分 ∵∠EAD＝∠BAC， ············································································ 5 分 ∴△AED∽△ABC． ············································································ 6 分 22. 解：(1)∵在 Rt△ABC 中，∠ACB＝90°，∠A＝30°， ∴∠B＝60°，AB＝2BC， ··································································· 1 分 ∵BC 为半圆 O 的直径， ∴∠CDB＝90°， ·············································································· 2 分 ∴∠BCD＝30°， ∴BC＝2BD， ···················································································· 3 分 ∴AB＝2BC＝4BD， ∴AD＝3BD； ···················································································· 4 分 (2)由(1)得∠B＝60°， ∴∠COD＝120°， ····································