1丰台区2020—2021学年第一学期期末练习初三数学评分标准及参考答案一、选择题（本题共24分，每小题3分）题号12345678答案BADBACCD二、填空题（本题共24分，每小题3分）9.y=x2-210.19∶11.0.88112.13.△BDA，△BCE14.815.在同圆或等圆中，同弧或等弧所对的圆周角相等16.1；3.23三、解答题（本题共52分，17-21题每小题5分，22题6分，23-25题每小题7分）17.解：（1） ，∴该二次函数图象顶点坐标为(2，-1).·············································································（2）如图：·············································································（3）-1≤y<3.·························································5分18.（1）证明： ，∴.又 ∠A=∠A，∴△ADE∽△ACB.·····················································2分（2）解： △ADE∽△ACB，∴∠ADE=∠ACB.······················································3分 ∠ADE=75°，∴∠ACB=75°.又 ∠B=55°，∴∠A=180°-∠ACB-∠B=50°.·······································5分19.解：（1）如图：·············································································2（2）如图：·············································································520.解：（1） 点D是矩形OABC的对角线交点，∴点D是矩形OABC的对角线AC的中点，又 A(4，0)，C(0，2)，∴点D的坐标为(2，1).··············································12 反比例函数的图象经过点D，∴，解得：k=2.·················································2分（2）由题意可得：点M的纵...
