A.Bắc Sơn - Võ Nhai.
B.Tuyên Quang.
C.Thái Nguyên.
D.Cao Bằng.

A.Nicaragua.
B.Cuba.
C.Achentina.
D.Chilê.

A.\({60^0}\)
B.\({30^0}\)
C.\({90^0}\)
D.\({45^0}\)

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

A.\( - 2\)
B.\(\dfrac{{18}}{{15}}\)
C.\(2\)
D.\(\dfrac{7}{2}\)

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

A.\(4\)
B.\(2\)
C.\(2\sqrt 6 \)
D.\( - 2\)

A.\(D\left( { - 1;1} \right)\) và \(C\left( { - 2;4} \right)\)
B.\(A\left( {1;1} \right)\) và \(B\left( {2;4} \right)\)
C.\(A\left( {1;1} \right)\) và \(C\left( { - 2;4} \right)\)
D.\(D\left( { - 1;1} \right)\) và \(B\left( {2;4} \right)\)

A.\(\dfrac{3}{5}\)
B.\(\dfrac{5}{3}\)
C.\(\dfrac{4}{3}\)
D.\(\dfrac{3}{4}\)

A.\(\left\{ \begin{array}{l}x = 3\\x + 2y = 0\end{array} \right.\)
B.\(\left\{ \begin{array}{l}x + y = 3\\2x + 2y = 9\end{array} \right.\)
C.\(\left\{ \begin{array}{l}x + y = 3\\2y = 0\end{array} \right.\)
D.\(\left\{ \begin{array}{l}x + y = 3\\2x + 2y = 6\end{array} \right.\)