A.\(4\pi {a^2}\)  
B.\(3\pi {a^2}\)  
C.\(2\pi {a^2}\)  
D.\(\pi {a^2}\)

A.\(x + y + 2z - 15 = 0\)  
B.\(x + y + 2z - 9 = 0\)  
C.\(x + y + 2z = 0\)  
D.\(x + y + 2z + 10 = 0\)

A.\(\dfrac{{\pi {a^3}}}{4}\)  
B.\(\dfrac{{\pi {a^3}}}{3}\)   
C.\(\dfrac{{\pi {a^3}}}{{12}}\)  
D.\(\pi {a^3}\)

A.\(7\)
B.\(6\)
C.\(5\)
D.\(8\)

A.\(m < 0\)  
B.\(0 < m < 1\)   
C.\(\left[ \begin{array}{l}m < 0\\m > 1\end{array} \right.\)  
D.\(m > 1\)

A.\(\dfrac{{2a}}{3}\)  
B.\(a\sqrt 3 \)   
C.\(\dfrac{{3a}}{4}\)  
D.\(\dfrac{{a\sqrt 3 }}{2}\)

A.\(\left[ \begin{array}{l}m = 1\\m =  - 2\end{array} \right.\)  
B.\(\left[ \begin{array}{l}m = 1\\m = 2\end{array} \right.\)   
C.\(\left[ \begin{array}{l}m =  - 1\\m = 2\end{array} \right.\)  
D.\(\left[ \begin{array}{l}m =  - 1\\m =  - 2\end{array} \right.\)

A.\(4\)
B.\(3\)
C.\(2\)
D.\(1\)

A.\(2\)  
B.\(8\)   
C.\(4\)  
D.\(6\)

A.\(1\)  
B.\( - 1\)   
C.\(\dfrac{1}{2}\)  
D.\( - \dfrac{1}{2}\)