2012年福州市初中毕业班质量检查数学试卷参考答案及评分标准

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1、2012年福州市初中毕业班质量检查数学试卷参考答案及评分标准一、选择题 1．A  2．B  3．C  4．C  5．D  6．A  7．D  8．A  9．B  10．C二、填空题：11．    12．8     13．    14.1    15．3三、解答题：16．（1）解：      = ················································································· 4分      =.··························

2、············································································· 7分（2）解：      = ··················································································· 4分      =,···············································································

3、····················· 5分当时，原式==5．························································· 7分17．（1）证明：∵AB与CD是平行四边形ABCD的对边，∴AB∥CD，······················································································· 2分∴∠F=∠FAB．······································

4、·············································· 4分∵E是BC的中点， ∴BE=CE,····························································· 5分又∵ ∠AEB=∠FEC， ······································································· 6分∴ △ABE≌△FCE．····································

5、······································· 7分（2）解：如图，a =45°，β=60°，AD＝80．在Rt△ADB中,∵， ∴．············ 2分在Rt△ADC中,∵,      ∴．······· 5分∴．答：这栋楼高约为218.6m．  ·················· 7分18．（1）=   25   %，90º ．··········································································· 2

6、分    补全条形图.····································································································· 4分（2）众数是5，中位数是5．·········································································· 8分（3）该市初一学生第一学期社会实践活动时间不少于5天的人数约是：（人）．························

7、······················· 12分19．（1）证法一：连接AE, ·································· 1分∵AC为⊙O的直径,∴∠AEC=90º,即AE⊥BC. ···························· 4分∵AB=AC,∴BE=CE，即点E为BC的中点．················ 6分证法二：连接OE， ····································· 1分∵OE=OC,∴∠C=∠OEC.∵AB=AC,∴∠C=∠B,∴∠B=

8、∠OEC,∴OE∥AB. ················································ 4分∴,∴EC=BE,即点E为BC的中点.·················· 6分⑵∵∠COD=80º,∴∠DAC=40º.·············