A.\(y = \cos x\)
B.\(y = {\cos ^2}x\)
C.\(y = \sin 2x\)
D.\(y = {\sin ^2}x\)

A.\(A = 192\)
B.\(A = 3\)
C.\(A = 156\)
D.\(A = 12\)

A.\(0\)
B.\(1\)
C.\(2\)
D.\(3\)

A.\( - 13\)
B.\(13\)
C.\( - 10\)
D.\(10\)

A.\(1 < n < 2021\)
B.\(0 < n < 1\)
C.\(n > 2021\)
D.\(0 < n < 2021\)

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

A.\(x = 3\)
B.\(x = 0\)
C.\(x = 1\)
D.\(x =  - 1\)

A.\(2\)
B.\(4\)
C.Vô số
D.\(1\)

A.\(498\)
B.\(462\)
C.\(504\)
D.\(426\)

A.\(2a\)
B.\(\dfrac{{a\sqrt {66} }}{{11}}\)
C.\(\dfrac{{11a}}{6}\)
D.\(\dfrac{{2a\sqrt {33} }}{{11}}\)