优优班--学霸训练营 > 知识点挑题
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            • 1.

              如图,\({ABCD}{-}A_{1}B_{1}C_{1}D_{1}\)为正方体,下面结论错误的是\(({  })\)



              A.\({BD}{/\!/}\)平面\(CB_{1}D_{1}\)
              B.\(AC_{1}{⊥}{BD}\)
              C.\(AC_{1}{⊥}\)平面\(CB_{1}D_{1}\)
              D.异面直线\(AD\)与\(CB_{1}\)所成的角为\(60^{{∘}}\)
            • 2.

              已知四面体\(S-ABC\)的顶点\(S\)与底面\(\Delta ABC\)各边距离都相等,若点\(S\)在底面\(\Delta ABC\)上的射影在\(\Delta ABC\)的形内,则该点的射影为\(\Delta ABC(\)   \()\)

              A. 垂心         
              B.重心         
              C.内心          
              D. 中心
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