A.\(\dfrac{1}{4}\).
B.\(\dfrac{1}{2}\).
C.\(\dfrac{{\sqrt 3 }}{2}\).
D.\(\dfrac{{\sqrt 2 }}{2}\) .

A.\(-2\)
B.\(15\)
C.\(2\)
D.\(-15\)

A.\({65^0}\).
B.\({35^0}\).
C.\({55^0}\).
D.\({45^0}\).

A.\(8\,\,\left( {cm} \right)\).
B.\(6\,\,\left( {cm} \right)\).   
C.\(2\,\,\,\left( {cm} \right)\).         
D.\(16\,\,\left( {cm} \right)\).

A.\(\Delta  = 88\).
B.\(\Delta  =  - 88\).
C.\(\Delta  = 22\).
D.\(\Delta  = 40\).

A.\(3\,\,\,\left( {cm} \right)\).
B.\(6\,\,\,\left( {cm} \right)\). 
C.\(5\,\,\,\left( {cm} \right)\).        
D.\(4\,\,\left( {cm} \right)\) .

A.\(\left( {x;y} \right) = \left( {1; - 2} \right).\)
B.\(\left( {x;y} \right) = \left( {1; - 1} \right).\)
C.\(\left( {x;y} \right) = \left( {1;2} \right).\)
D.\(\left( {x;y} \right) = \left( {1; - 3} \right).\)

A.\(A = \sqrt x \)
B.\(A = \dfrac{{\sqrt x }}{{\sqrt x  - 3}}\)
C.\(A = \sqrt x  - 3\)
D.\(A = \dfrac{{\sqrt x  - 3}}{{\sqrt x }}\)

A.\(x =  - 4\,;\,\,x =  - 1\)
B.\(x = 4\,;\,\,x = 1\)
C.\(x = 4\,;\,\,x =  - 1\)
D.\(x =  - 4\,;\,\,x = 1\)

A.\( - 11\)
B.\(11\) và \( - 11\).
C.\(11\).                            
D.\(12\).