4．已知点M (－2，3 )在双曲线上，则下列各点一定在该双曲线上的是

(A)(3，-2 )　 　 (B)(-2，-3 )　 (C)(2，3 )　　 D)(3，2) 　　

3．如图所示，把一个长方形纸片沿EF折叠后，点D，C分别落在D′，C′的位置．若∠EFB＝65°，则∠AED′等于　 　

(A) 70°　　　 　　　　 (B) 65°　　 　　　

(C) 50°　　 　　　　　　 (D) 25°　 　　　　

2．计算的结果是

(A)　 (B)　 　(C) 　(D)　　　 　　

1．某市2009年元旦的最高气温为2℃，最低气温为－8℃，那么这天的最高气温比最低气温高

(A)-10℃　　 (B)-6℃　　 　(C)6℃　　 (D)10℃ 　

25．(本小题满分12分)

解：(1)①轴，轴，

四边形为矩形．

轴，轴，

四边形为矩形．

轴，轴，

四边形均为矩形．············ 1分

，

，

．

．

，

　 ，

．······························································································ 2分

②由(1)知．

．

．············································································································ 4分

，

．································································································ 5分

．

．············································································································· 6分

轴，

四边形是平行四边形．

．············································································································· 7分

同理．

．············································································································· 8分

(2)与仍然相等．························································································· 9分

，

，

又，

．································· 10分

．

．

，

．

．

．············································································································ 11分

轴，

四边形是平行四边形．

．

同理．

．·········································································································· 12分

24．(本小题满分11分)

解：(1)设抛物线的解析式为．······················································· 1分

将代入上式，得．

解，得．············································································································ 2分

抛物线的解析式为．

即．··································································································· 3分

(2)连接，交直线于点．

点与点关于直线 对称，

．······························································ 4分

．

由“两点之间，线段最短”的原理可知：

此时最小，点的位置即为所求．················ 5分

设直线的解析式为，

由直线过点，，得

解这个方程组，得

直线的解析式为．············································································· 6分

由(1)知：对称轴为，即．

将代入，得．

点的坐标为(1，2)．···························································································· 7分

说明：用相似三角形或三角函数求点的坐标也可，答案正确给2分．

(3)①连接．设直线与轴的交点记为点．

由(1)知：当最小时，点的坐标为(1，2)．

．

．·························································································· 8分

．

．

与相切．······································································································ 9分

②．················································································································· 11分

23．(本小题满分10分)

解：(1)四边形是正方形．······················· 1分

证明：四边形是正方形，

.

，

．··································· 2分

．········ 3分

．··································· 4分

四边形是菱形．····································· 5分

由知．

，

．

．········································································································ 6分

四边形是正方形．························································································· 7分

(2)1．····················································································································· 10分

22．(本小题满分10分)

解：(1)设购买乙种电冰箱台，则购买甲种电冰箱台，

丙种电冰箱台，根据题意，列不等式：·························································· 1分

．······················································· 3分

解这个不等式，得．·························································································· 4分

至少购进乙种电冰箱14台．······················································································ 5分

(2)根据题意，得．·············································································· 6分

解这个不等式，得．·························································································· 7分

由(1)知．

．

又为正整数，

．··········································································································· 8分

所以，有三种购买方案：

方案一：甲种电冰箱为28台，乙种电冰箱为14台，丙种电冰箱为38台；

方案二：甲种电冰箱为30台，乙种电冰箱为15台，丙种电冰箱为35台；

方案三：甲种电冰箱为32台，乙种电冰箱为16台，丙种电冰箱为32台．·················· 10分

21．(本小题满分9分)

解：过点A作，垂足为D．························ 1分

在中，，，

∴．···················· 3分

．······················ 5分

在中，，

∴································ 8分

(海里)

答：之间的距离约为21.6海里．········································································· 9分

20．(本小题满分7分)

解：摸出两个异色小球的概率与摸出两个同色小球的概率不相等．································ 1分

画树状图如下(画出一种情况即可)：

　　······································· 4分

∴摸出两个异色小球的概率为，················································································ 5分

摸出两个同色小球的概率．······················································································· 6分

即摸出两个异色小球的概率与摸出两个同色小球的概率不相等．··································· 7分