如图,已知某水库大坝迎水坡AB的坡度为α=47°,PQ为水库水面(点P在AB上),AE⊥PQ于E,PA=20米,求水深EA.(精确到0.1米)
考点分析:
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先化简再求值:
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(
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+2)-(
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-2)
2,其中a=
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.
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计算:
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000855588059154/SYS201311030008555880591018_ST/0.png)
-2×
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-2sin45°.
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四边形ABCD为边长等于1的菱形,顺次连接它的各边中点组成四边形EFGH(四边形EFGH称为原四边形的中点四边形),再顺次连接四边形EFGH的各边中点组成第二个中点四边形,…,则按上述规律组成的第八个中点四边形的边长等于
.
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