26．(1)解：由得点坐标为

由得点坐标为

∴··················································································· (2分)

由解得∴点的坐标为···································· (3分)

∴··························································· (4分)

　 (2)解：∵点在上且

　　　　　　 ∴点坐标为······················································································ (5分)

又∵点在上且

∴点坐标为······················································································ (6分)

∴··········································································· (7分)

　 (3)解法一：当时，如图1，矩形与重叠部分为五边形(时，为四边形)．过作于，则

∴即∴

∴

即··································································· (10分)

25．解：(1)····································································································· (1分)

证明：(证法一)

由旋转可知，

∴···························································· (3分)

∴又

∴即··································· (4分)

(证法二)

由旋转可知，而

∴···························································· (3分)

∴∴

即·········································································· (4分)

　　　 (2)四边形是菱形. ················································································· (5分)

证明：同理

∴四边形是平行四边形. ························································· (7分)

又∴四边形是菱形. ··········································· (8分)

　　　 (3)(解法一)过点作于点，则

在中，

……(10分)

由(2)知四边形是菱形，

∴

∴························································ (12分)

(解法二)∴

在中，

　······················································ (10分)

∴································································ (12分)

(其它解法可参照给分)

24．解：(1)由题意，得：解得················································ (2分)

　　　　　 　∴····················································································· (3分)

(2)

　　 ∴··················································································· (5分)

　　　 ∴时，有最大值为6.6. ····························· (7分)

∴(吨).

答：甲、乙两种水果的进货量分别为4吨和6吨时，获得的销售利润之和最大，最大利润是6.6万元. ························································································································ (8分)

23．解：分别过作于于过作于则四边形为矩形．

∴

在中，

∴·············································································································· (3分)

在中，············································ (6分)

∴············································· (7分)

答：水深约为6.7米．·································································································· (8分)

(其它解法可参照给分)

22．解：(1)10，50；········································································································ (2分)

　　　 (2)解：解法一(树状图)：

··········································································································································· (6分)

从上图可以看出，共有12种可能结果，其中大于或等于30元共有8种可能结果，因此(不低于30元)=····························································································································· (8分)

解法二(列表法)：

第一次 第二次	0	10	20	30
0		10	20	30
10	10		30	40
20	20	30		50
30	30	40	50

····························································································································· (6分)

(以下过程同“解法一”)····················································································· (8分)

21．(1)935.7，859.0；······································································································ (4分)

　 (2)解：2004~2008移动电话年末用户逐年递增．

　　　　　 2008年末固定电话用户达803.0万户．······················································· (8分)

　　　　　 (注：答案不唯一，只要符合数据特征即可得分)

20．解：(1)；·········································································································· (2分)

(2)答案不唯一，以下提供三种图案．

(注：如果花边图案中四个图案均与基本图案相同，则本小题只给2分；未画满四个“田”字格的，每缺1个扣1分．)

19．(1)解：原式=···································································· (2分)

　　　　　　　 =······································································· (3分)

　　　　　　　 =．······························································································· (4分)

(2)解：原式=············································································ (2分)

　　　　　　 =·························································································· (3分)

　　　　　　 =1．·········································································································· (4分)

(3)解：移项，得配方，得····················································· (2分)

　　　　 　∴∴······································································ (4分)

　　　　　 (注：此题还可用公式法，分解因式法求解，请参照给分)

6．210　　　 7．(9，0)　　　 8．8　　　 9．　　　 10．

1．＞　　　 2．　　　 3．答案不唯一，如　　　 4．　　 　5．30