如图,某幢大楼顶部有一块广告牌CD,甲乙两人分别在相距8米的A、B两处测得D点和C点的仰角分别为45°和60°,且A、B、E三点在一条直线上,若BE=15米,求这块广告牌的高度.(取
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≈1.73,计算结果保留整数)
考点分析:
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计算:
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+4cos60°sin45°-
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.
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如图,AB、AC是圆的两条弦,AD是圆的一条直径,且AD平分∠BAC,下列结论中不一定正确的是( )
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000756704092272/SYS201311030007567040922019_ST/images0.png)
A.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000756704092272/SYS201311030007567040922019_ST/0.png)
B.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000756704092272/SYS201311030007567040922019_ST/1.png)
C.BC⊥AD
D.∠B=∠C
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一人乘雪橇沿坡比1:
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000756704092272/SYS201311030007567040922018_ST/0.png)
的斜坡笔直滑下,滑下的距离s(米)与时间t(秒)间的关系为s=10t+2t
2,若滑到坡底的时间为4秒,则此人下降的高度为( )
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000756704092272/SYS201311030007567040922018_ST/images1.png)
A.72m
B.36
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000756704092272/SYS201311030007567040922018_ST/1.png)
m
C.36m
D.18
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131103000756704092272/SYS201311030007567040922018_ST/2.png)
m
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