Bài tập 5 trang 95 SGK Hình học 12

A. \(\dfrac{2}{{\sqrt {13} }}.\)     

B. \(\dfrac{1}{{\sqrt {13} }}.\)

C. \(\dfrac{{\sqrt {13} }}{2}.\)     

D. \(\dfrac{{3\sqrt {13} }}{{13}}.\)

A. \(\cos \left( {\overrightarrow b ,\overrightarrow c } \right) = \dfrac{{\sqrt 6 }}{3}.\)    

B. \(\overrightarrow a  + \overrightarrow b  + \overrightarrow c  = \overrightarrow 0 .\)                      

A. \(\overrightarrow a ,\overrightarrow b ,\overrightarrow c \) đồng phẳng.        

D. \(\overrightarrow a .\overrightarrow b  = 1.\)

A. \(I(\dfrac{8}{3};\dfrac{5}{3};\dfrac{8}{3})\).       

B. \(I(\dfrac{5}{3};\dfrac{8}{3};\dfrac{8}{3})\).

C. \(I( - \dfrac{5}{3};\dfrac{8}{3};\dfrac{8}{3}).\)   

D. \(I(\dfrac{8}{3};\dfrac{8}{3};\dfrac{5}{3})\).

A. \(D(0;1;3)\).           

B. \(D(0;3;1)\).           

C. \(D(0; - 3;1)\).        

D. \(D(0;3; - 1)\).

A. \(43.\).         

B. \(44.\).        

C. \(42.\).        

D. \(45.\)

A. \(\left( {3;\dfrac{8}{3}; - \dfrac{8}{3}} \right).\)   

B. \(\left( {3;\dfrac{8}{3};\dfrac{8}{3}} \right).\)      

C. \(\left( {3;3; - \dfrac{8}{3}} \right).\)     

D. \(\left( {1;2;\dfrac{1}{3}} \right).\)

A. \(\left( {1;0;0} \right).\)      

B. \(\left( {0;0;1} \right).\)      

C. \(\left( {0;1;0} \right).\)      

D. \(\left( {0;0;0} \right).\)