of rural drinking water sources, protection of drinking water sources in rural areas by the end of the delimitation of tAB=8,AD=6,将纸片折叠,使得AD边落在AB边上,折痕为AE,再将△AED沿DE向右翻折,AE与BC的交点为F,则△CEF的面积为( )
9.(3分)(2015•呼和浩特)如图是某几何体的三视图,根据图中所标的数据求得该几何体的体积为( ) of rural drinking water sources, protection of drinking water sources in rural areas by the end of the delimitation of the scope of protection, complete with warning signs, isolating network protection facilities of rural drinking water sources, protection of drinking water sources in rural areas by the end of the delimitation of the scope of protection, complete with warning signs, isolating network protection facilities第3页(共70页) of rural drinking water sources, protection of drinking water sources in rural areas by the end of the delimitation of the scope of protection, complete with warning signs, isolating network protection facilities
16.(3分)(2015•呼和浩特)以下四个命题: ①若一个角的两边和另一个角的两边分别互相垂直,则这两个角互补; ②边数相等的两个正多边形一定相似; ③等腰三角形ABC中,D是底边BC上一点,E是一腰AC上的一点,若∠BAD=60°且AD=AE,则∠EDC=30°; ④任意三角形的外接圆的圆心一定是三角形三条边的垂直平分线的交点. 其中正确命题的序号为 . of rural drinking water sources, protection of drinking water sources in rural areas by the end of the delimitation of the scope of protection, complete with warning signs, isolating network protection facilitie