共50条信息
如图,以长方体\(ABCD-{{A}_{1}}{{B}_{1}}{{C}_{1}}{{D}_{1}}\)的顶点\(D\)为坐标原点,过点\(D\)的三条棱所在直线为坐标轴建立空间直角坐标系\(.\) 若\(\overrightarrow{D{{B}_{1}}}\)的坐标为\(\left(3,4,5\right) \),则\(\overrightarrow{{{A}_{1}}C}\)的坐标是
如图,四棱锥\(P-ABCD\)中,底面\(ABCD\)为矩形,侧面\(PAD\)为正三角形,且平面\(PAD⊥\)平面\(ABCD\),\(E\)为\(PD\)中点,\(AD=2\).
\((\)Ⅰ\()\)求证:平面\(AEC⊥\)平面\(PCD\).
\((\)Ⅱ\()\)若二面角\(A-PC-E\)的平面角大小\(θ\)满足\(\cos θ= \dfrac{ \sqrt{2}}{4}\),求四棱锥\(P-ABCD\)的体积.
点\(P(1,1,1) \)关于\(xOy \)平面的对称点为\({R}_{1} \),则点\({R}_{1} \)关于\(z \)轴的对称点\({p}_{2} \)的坐标是( )
如图,三棱台\(DEF-ABC\)中,底面是以\(AB\)为斜边的直角三角形,\(FC⊥\)底面\(ABC\),\(AB=2DE\),\(G\),\(H\)分别为\(AC\),\(BC\)的中点.
如图,长方体\(ABCD-{{A}_{1}}{{B}_{1}}{{C}_{1}}{{D}_{1}}\)在空间直角坐标系\(Oxyz\)中,若\(AB=BC=2,A{{A}_{1}}=1\),则点\({{B}_{1}}\)的坐标是\((\) \()\)
\(A\)\((-3,1,5)\),\(B\)\((4,3,1)\)的中点坐标是( )
如甲图所示,在矩形\(ABCD\)中,\(AB=4\),\(AD=2\),\(E\)是\(CD\)的中点,将\(\triangle ADE\)沿\(AE\)折起到\(\triangle D_{1}AE\)位置,使平面\(D_{1}AE⊥\)平面\(ABCE\),得到乙图所示的四棱锥\(D_{1}-ABCE\).
甲 乙
\((\)Ⅰ\()\)求证:\(BE⊥\)平面\(D_{1}AE\);
\((\)Ⅱ\()\)求二面角\(A-D_{1}E-C\)的余弦值.
设\(A(3,2,1)\),\(B(1,0,5)\),\(C(0,2,1)\),\(AB\)的中点为\(M\),则\(|CM|=\)( )
若\( \overrightarrow{a} =(2,3,-1)\),\( \overrightarrow{b} =(-2,1,3)\),则\( \overrightarrow{a} - \overrightarrow{b} =\)_______________________ ; \(| \overrightarrow{a} - \overrightarrow{b} \)\(|= \)_______ .
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