A. \(\overrightarrow a .\overrightarrow b = \left| {\overrightarrow a } \right|\left| {\overrightarrow b } \right|\)
B. \(\overrightarrow a .\overrightarrow b = - \left| {\overrightarrow a } \right|\left| {\overrightarrow b } \right|\)
C. \(\overrightarrow a .\overrightarrow b = 1\)
D. \(\overrightarrow a .\overrightarrow b = 0\)
A. \(\cos (\overrightarrow a ,\overrightarrow b ) = \frac{{{a_1}{b_2} + {a_2}{b_1}}}{{\sqrt {{a_1}^2 + {a_2}^2} .\sqrt {{b_1}^2 + {b_2}^2} }}\)
B. \(\overrightarrow a .\overrightarrow b = {a_1}{b_1} + {a_2}{b_2}\)
C. \(\overrightarrow a \bot \overrightarrow b \Leftrightarrow {a_1}{b_1} + {a_2}{b_2} = 0\)
D. \(\left| {\overrightarrow a } \right| = \sqrt {{a_1}^2 + {a_2}^2} \)
A. \(a > b \Leftrightarrow {a^2} > {b^2}\)
B. \(a > b \Leftrightarrow a - b > 0\)
C. \(a > b > 0 \Rightarrow \frac{1}{a} < \frac{1}{b}\)
D. \(a > b \Leftrightarrow \sqrt[3]{a} > \sqrt[3]{b}\)
A.
\(\left\{ \begin{array}{l}
a > b > 0\\
c > d > 0
\end{array} \right. \Rightarrow ac > bd\)
B.
\(\left\{ \begin{array}{l}
a > b\\
c > d
\end{array} \right. \Rightarrow \frac{a}{c} > \frac{b}{d}\)
C.
\(\left\{ \begin{array}{l}
a > b\\
c > d
\end{array} \right. \Rightarrow ac > bd\)
D.
\(\left\{ \begin{array}{l}
a > b\\
c > d
\end{array} \right. \Rightarrow a - c > b - d\)
A. \(\cos \alpha = \cos ({180^0} - \alpha )\)
B. \(\tan \alpha = \tan ({180^0} - \alpha )\)
C. \(\sin \alpha = \sin ({180^0} - \alpha )\)
D. \(\cot \alpha = \cot ({180^0} - \alpha )\)
A. \(\frac{{{y_0}}}{{{x_0}}}\)
B. \(\frac{{{x_0}}}{{{y_0}}}\)
C. x0
D. y0
A. \(\left| {\overrightarrow a } \right|\left| {\overrightarrow b } \right|\cos (\overrightarrow a ,\overrightarrow b )\)
B. \(\left| {\overrightarrow a } \right|\left| {\overrightarrow b } \right|\cos (\overrightarrow a ,\overrightarrow b )\)
C. \(\left| {\overrightarrow a } \right|\left| {\overrightarrow b } \right|\sin (\overrightarrow a ,\overrightarrow b )\)
D. \(\left| {\overrightarrow a } \right|\left| {\overrightarrow b } \right|\)
A. x > 1
B. \(x \ge 1\)
C. \(x \le 1\)
D. x < 1
A.
\(\left\{ \begin{array}{l}
a = 0\\
b > 0
\end{array} \right.\)
B.
\(\left\{ \begin{array}{l}
a = 0\\
b < 0
\end{array} \right.\)
C.
\(\left\{ \begin{array}{l}
a > 0\\
b > 0
\end{array} \right.\)
D.
\(\left\{ \begin{array}{l}
a = 0\\
b \ge 0
\end{array} \right.\)
A. -6
B. 6
C. 2
D. 3
A. a = b = c
B. \(a.b \ne 0\)
C. a = 0
D. \(a \ne 0\)
A. \({S_{\Delta ABC}} = \frac{1}{2}bc\sin A$\)
B. \(\frac{a}{{\sin A}} = \frac{b}{{\sin B}} = \frac{c}{{\sin C}}\)
C. \({a^2} + 2bc\cos B = {b^2} + {c^2}\)
D. \(\cos A = \frac{{{b^2} + {c^2} - {a^2}}}{{2bc}}\)
A.
\(\left\{ \begin{array}{l}
a < b\\
c < d
\end{array} \right. \Rightarrow ac < bd\)
B. \(a < b \Leftrightarrow a + c < b + c\)
C. \(a < b \Leftrightarrow ac < bc\)
D. \(a < b \Leftrightarro\) ac > bc$
A. 1
B. 0
C. Vô số
D. 2
A. Nếu \({b^2} + {c^2} - {a^2} < 0\) thì góc A nhọn.
B. Nếu \({b^2} + {c^2} - {a^2} < 0\) thì góc A vuông.
C. Nếu \({b^2} + {c^2} - {a^2} > 0\) thì góc A tù.
D. Nếu \({b^2} + {c^2} - {a^2} > 0\) thì góc A nhọn.
A. \(a = 2R\tan A\)
B. \(a = 2R\cos A\)
C. \(a = R\sin A\)
D. \(a = 2R\sin A\)
A. \(\left[ { - \frac{1}{2}; + \infty } \right)\)
B. \(\left[ {\frac{1}{2}; + \infty } \right)\)
C. \(\left( { - \infty ;\frac{1}{2}} \right]\)
D. \(\left( {\frac{1}{2}; + \infty } \right)\)
A. \({b^2} - 4 < 0\)
B. \(\left| b \right| \le 2\)
C. \(\forall b \in R\)
D. \({b^2} - 4 > 0\)
A. \(\left[ { - 1;1} \right]\)
B. \(\left( { - \infty ; + \infty } \right)\)
C. \(\left( { - 1;1} \right)\)
D. \(\left( { - \infty ; - 1} \right] \cup \left[ {1; + \infty } \right)\)
A. \(\left( { - 1;0} \right] \cup \left( {2; + \infty } \right)\)
B. \(\left( { - \infty ; - 1} \right) \cup \left[ {2; + \infty } \right)\)
C. \(\left( { - \infty ;0} \right) \cup \left[ {2; + \infty } \right)\)
D. \(\left( { - 1;0} \right] \cup \left[ {2; + \infty } \right)\)
A. \(\left( { - \infty ; - 2} \right] \cup \left[ {3; + \infty } \right)\)
B. \(\left( { - \infty ; - 2} \right) \cup \left[ {3; + \infty } \right)\)
C. \(\left( { - \infty ; - 2} \right] \cup \left( {3; + \infty } \right)\)
D. [-2; 3]
A. 4
B. -4
C. 8
D. 6
A. \(\frac{{ - 3}}{5}$\)
B. \(\frac{1}{5}\)
C. \(\frac{{ - 1}}{5}\)
D. \(\frac{3}{5}\)
A. -3
B. 2
C. -1
D. -6
A. 4
B. -5
C. 3
D. 5
A. 300
B. 600
C. 1200
D. 450
A. 12
B. -12
C. -9
D. 18
A. a2
B. \( - \frac{{{a^2}}}{2}\)
C. - a2
D. \(\frac{{{a^2}}}{2}\)
A. 9
B. 7
C. 2
D. -7
A. 2018.
B. 2021
C. 2020
D. 2019
A. 1/3
B. 2/3
C. 1
D. -2/3
A. R = a
B. \(R = \frac{{a\sqrt 3 }}{2}\)
C. \(R = \frac{{a\sqrt 6 }}{3}\)
D. \(R = \frac{{a\sqrt 3 }}{3}\)
A. 2
B. 3
C. 0
D. -1
A. R = 2a
B. R = a
C. \(R = a\sqrt 3 \)
D. \(R = a\sqrt 7 \)
A. \(S = \left( { - \frac{3}{2};0} \right) \cup (3; + \infty )\)
B. \(S = \left[ {0;3} \right)\)
C. \(S = \left[ { - \frac{3}{2};2} \right)\)
D. \(S = \left[ { - \frac{3}{2};3} \right)\)
A. 2
B. 1
C. 4
D. -2
A. 4
B. 3
C. 2
D. 5
A. \(\sqrt 2 \)
B. \(2\sqrt 2 \)
C. 0
D. \(\frac{{14}}{5}\)
A. 4
B. \(\sqrt 3 \)
C. \(\sqrt 6 \)
D. \(\sqrt 7 \)
A. 4
B. -1
C. 3
D. 2
A. 3
B. 1
C. 4
D. -2
A. 5
B. 3
C. 4
D. 6
A. -3
B. \( - \frac{5}{2}.\)
C. -5
D. \(\sqrt {17} .\)
A. \( - \frac{{22}}{{25}}\)
B. \( - \frac{{23}}{{25}}\)
C. \( - \frac{{21}}{{25}}\)
D. \( - \frac{{24}}{{25}}\)
A. \(a + b = \frac{{1 + \sqrt 5 }}{2}.\)
B. \(a + b > \frac{{ - 1 + \sqrt 5 }}{2}.\)
C. \(a + b > \frac{{1 + \sqrt 5 }}{2}.\)
D. \(a + b = \frac{{ - 1 + \sqrt 5 }}{2}.\)
A. 4/3
B. 1
C. 3/4
D. 5/3
A. \(\frac{{37}}{{50}}\)
B. \(\frac{{3}}{{4}}\)
C. \(\frac{{19}}{{25}}\)
D. \(\frac{{4}}{{3}}\)
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