Bài tập 13 trang 96 SGK Hình học 12

A. \(\overrightarrow b  = \left( { - 2; - 6; - 8} \right).\)          

B. \(\overrightarrow b  = \left( { - 2; - 6;8} \right).\)

C. \(\overrightarrow b  = \left( { - 2;6;8} \right).\)     

D. \(\overrightarrow b  = \left( {2; - 6; - 8} \right).\)

A. 0.                

B. \(\dfrac{2}{5}\).            

C. \(\dfrac{2}{{\sqrt 5 }}\).             

D. \( - \dfrac{2}{5}\).  

(A) \(2\) ;       

(B) \({2 \over 3}\);       

(C) \({4 \over 3}\);       

(D) \({2 \over 9}\) .

(A) \(d ⊥ (α)\) ;

(B) \(d\) cắt \( (α)\) ;

(C) \(d // (α)\) ;

(D) \(d ⊂ (α)\).

(A) d₁⊥ d₂               

(B) d₁ // d₂

(C) d₁ ≡ d₂             

(D) d₁ và d₂ chéo nhau.

(A)\(\left\{ \matrix{x = - 1 + 4t \hfill \cr y = - 2 + 3t \hfill \cr z = - 3 - 7t \hfill \cr} \right.\);

(B)\(\left\{ \matrix{x = 1 + 4t \hfill \cr y = 2 + 3t \hfill \cr z = 3 - 7t \hfill \cr} \right.\);

(C)\(\left\{ \matrix{x = 1 + 3t \hfill \cr y = 2 - 4t \hfill \cr z = 3 - 7t \hfill \cr} \right.\);

(D)\(\left\{ \matrix{x = - 1 + 8t \hfill \cr y = - 2 + 6t \hfill \cr z = - 3 - 14t. \hfill \cr} \right.\)

\((A)\left\{ \matrix{x = - 2 + 4t \hfill \cr y = - 6t \hfill \cr z = 1 + 2t \hfill \cr} \right.\)               

\((B)\left\{ \matrix{x = - 2 + 2t \hfill \cr y = - 3t \hfill \cr z = 1 + t \hfill \cr} \right.\);

\((C)\left\{ \matrix{x = 2 + 2t \hfill \cr y = - 3t \hfill \cr z = - 1 + t \hfill \cr} \right.\);               

\((D)\left\{ \matrix{x = 4 + 2t \hfill \cr y = - 6 - 3t \hfill \cr z = 2 + t \hfill \cr} \right.\).