设a>b>0,a
2+b
2=4ab,则
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282555747/SYS201310191105132825557001_ST/0.png)
的值等于
.
考点分析:
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同时抛掷两枚正方体骰子,所得点数之和为7的概率是
.
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(2007•台湾)如图,在地面上有一个钟,钟面的12个粗线刻度是整点时时针(短针)所指的位置.根据图中时针与分针(长针)的位置,该钟面所显示的时刻在下列哪范围内( )
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674032_ST/images0.png)
A.3点~4点
B.6点~7点
C.8点~9点
D.10点~11点
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(2007•台湾)以下是甲、乙两人证明
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/0.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/1.png)
≠
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/2.png)
的过程:
(甲)因为
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/3.png)
>
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/4.png)
=3,
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/5.png)
>
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/6.png)
=2,所以
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/7.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/8.png)
>3+2=5
且
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/9.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/10.png)
<
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/11.png)
=5
所以
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/12.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/13.png)
>5>
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/14.png)
故
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/15.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/16.png)
≠
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/17.png)
(乙)作一个直角三角形,两股长分别为
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/18.png)
、
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/19.png)
利用商高(勾股)定理(
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/20.png)
)
2+(
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/21.png)
)
2=15+8
得斜边长为
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/22.png)
因为
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/23.png)
、
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/24.png)
、
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/25.png)
为此三角形的三边长
所以
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/26.png)
+
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>
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019110513282467485/SYS201310191105132824674031_ST/28.png)
故
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+
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≠
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