2018-2019福州市质检答案

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1、2018—2019学年度福州市九年级质量检测数学试题答案及评分标准评分说明：1．本解答给出了一种或几种解法供参考，如果考生的解法与本解答不同，可根据试题的主要考查内容比照评分参考制定相应的评分细则．2．对于计算题，当考生的解答在某一步出现错误时，如果后继部分的解答未改变该题的内容和难度，可视影响的程度决定后继部分的给分，但不得超过该部分正确解答应给分数的一半；如果后继部分的解答有较严重的错误，就不再给分．3．解答右端所注分数，表示考生正确做到这一步应得的累加分数．4．只给整数分数．选择题和填空题不给中间分．一、选择题：每小

2、题4分，满分40分．1．A2．B3．D4．B5．C6．D7．C8．B9．C10．B二、填空题：每小题4分，满分24分．11．m(m2)(m2)12．正方体13．甲14．45115．4316．2注：12题答案不唯一，能够正确给出一种符合题意的几何体即可给分，如：某个面是正方形的长方体，底面直径和高相等的圆柱，等．三、解答题：本题共9小题，共86分．解答应写出文字说明、证明过程和演算步骤．317．解：原式331···························································

3、·········6分3311·············································································7分3．················································································8分18．证明：∵∠1∠2，∴∠ACB∠ACD．····································3分B在△ABC和△ADC中，BD，A1C2ACBACD

4、，ACAC，D∴△ABC≌△ADC(AAS)，·······················································6分∴CBCD．··········································································8分注：在全等的获得过程中，∠B＝∠D，AC＝AC，△ABC≌△ADC，各有1分．数学试题答案及评分参考第1页（共6页）2x1x2x119．解：原式2·····························

5、··································1分xx2x1x2····································································3分x(x1)x，·············································································5分x131当x31时，原式····················································6

6、分31131333．···················································8分320．解：BOCDA···········································3分如图，⊙O就是所求作的圆．·······················································4分证明：连接OD．∵BD平分∠ABC，∴∠CBD∠ABD．···············································

7、············5分∵OBOD，∴∠OBD∠ODB，∴∠CBD∠ODB，··························································6分∴OD∥BC，∴∠ODA∠ACB又∠ACB90°，∴∠ODA90°，即OD⊥AC．····································································7分∵点D是半径OD的外端点，∴AC与⊙O相切．·······························

8、·····························8分注：垂直平分线画对得1分，标注点O得1分，画出⊙O得1分；结论1分．21．（1）四边形ABB′A′是菱形．·································································1分证