[原创]六月jj，\有更新

加油努力

是在不好意思，有几题写的不清楚，误导大家了。我改了一下。

adeline82

8.一个3x3的表格，就是一个长方形里面有两条横线，两条竖线A点是长方形最左下角的一点，B点是最右上角的一点，C点是长方形里面两条线中最上面的一条和两条竖线中右边那条线的交点。问从A到B，并经过C点的路径的条数。

解法：A到C点：P4/(P2*P2) C到B：2

所以A到B经C共12

有人知道数学第19题怎么做得吗？

cutelee1974

12题和14题给个思路吧.谢谢了.明天就要上法场了.

[此贴子已经被作者于2006-6-20 20:22:08编辑过]

yaoyao99

8. see #20  http://forum.chasedream.com/dispbbs.asp?boardID=22&ID=175196&page=2     第 18 楼

12. Rug = x by y, floor = A by B =>
(A-x)*(B-y) + (A-x)*B = 72
1) A*B = 120
2) A+B = 44/2 = 22
can't solve for both x and y
E

14, With condition 1 and 2, you can solve for the x intersect of the circle and know that it is less than -2 so you know that the line goes through the inside of the circle.

yaoyao99

[attachimg]47954[/attachimg]

AD = 2, let BD = x, and raidus of circle = r

(ADB is 90 degree) AD^2 + BD^2 = AB^2 => 2^2 + x^2 = AB^2

(BAC is 90 degree) AB^2 + AC^2 = BC^2 => AB^2 + AD^2 + DC^2 = (2r)^2 => AB^2 = (2r)^2 - 2^2 - (2r-x)^2

combine the 2 equations, you can figure out that x > 1.5 so the line intersects the circle.

[此贴子已经被作者于2006-6-20 22:15:12编辑过]

numberunique

yao yao 终于出现拉  听说考了很牛的分数

stellaleigh

哈哈，恭喜恭喜。好强的记忆力！

rosierosie

哦？14题是问得K经过圆心还是K穿过圆？？

yaoyao99

Hmm. I think it intersects. 

[此贴子已经被作者于2006-6-20 22:15:44编辑过]

cutelee1974

谢谢YAOYAO.14题还是不太明白,就记答案吧.