A. \({b^2} = {a^2} + {c^2} - 2ac\cos B\)
B. \({a^2} = {b^2} + {c^2} - 2bc\cos A\)
C. \({c^2} = {b^2} + {a^2} + 2ab\cos C\)
D. \({c^2} = {b^2} + {a^2} - 2ab\cos C\)
A. \(R = \frac{a}{{\sin A}}\)
B. \(R = \frac{b}{{\sin A}}\)
C. \(R = \frac{a}{{2\sin A}}\)
D. \(R = \frac{b}{{2\sin A}}\)
A. \(m_a^2 = \frac{{{b^2} + {c^2}}}{2} + \frac{{{a^2}}}{4}\)
B. \(m_a^2 = \frac{{{a^2} + {c^2}}}{2} - \frac{{{b^2}}}{4}\)
C. \(m_a^2 = \frac{{2{c^2} + 2{b^2} - {a^2}}}{4}\)
D. \(m_a^2 = \frac{{{a^2} + {b^2}}}{2} - \frac{{{c^2}}}{4}\)
A. \(S = \sqrt {p\left( {p - a} \right)\left( {p - b} \right)\left( {p - c} \right)} \)
B. \(S = \sqrt {\left( {p - a} \right)\left( {p - b} \right)\left( {p - c} \right)} \)
C. \(S = p\left( {p - a} \right)\left( {p - b} \right)\left( {p - c} \right)\)
D. \(S = \left( {p - a} \right)\left( {p - b} \right)\left( {p - c} \right)\)
A. \(\cos A = \frac{{{b^2} + {c^2} - {a^2}}}{{bc}}\)
B. \(\cos A = \frac{{{b^2} + {c^2} - {a^2}}}{{2bc}}\)
C. \(\cos A = \frac{{{a^2} + {b^2} + {c^2}}}{{bc}}\)
D. \(\cos A = \frac{{{a^2} + {b^2} + {c^2}}}{{2bc}}\)
A. \(\overrightarrow n = \left( {1;3} \right)\)
B. \(\overrightarrow n = \left( { - 3;1} \right)\)
C. \(\overrightarrow n = \left( {1; - 3} \right)\)
D. \(\overrightarrow n = \left( {3;1} \right)\)
A. \(M\left( {1; - 2} \right)\)
B. \(N\left( {3;5} \right)\)
C. \(P\left( { - 1; - 2} \right)\)
D. \(Q\left( { - 3;5} \right)\)
A. \(\overrightarrow u = \left( {1; - 3} \right)\)
B. \(\overrightarrow u = \left( { - 2;3} \right)\)
C. \(\overrightarrow u = \left( { - 1;3} \right)\)
D. \(\overrightarrow u = \left( { - 2; - 3} \right)\)
A. 49
B. \(\sqrt {97} \)
C. 7
D. \(\sqrt {61} \)
A. \(\sqrt 2 \)
B. \(2\sqrt 2 \)
C. \(\sqrt 3 \)
D. \(2\sqrt 3 \)
A. 60
B. \(60\sqrt 3 \)
C. 30
D. \(30\sqrt 3 \)
A.
\(\left\{ {\begin{array}{*{20}{c}}
{x = t}\\
{y = 2 + t}
\end{array}\,\,\left( {t \in R} \right)} \right.\)
B.
\(\left\{ {\begin{array}{*{20}{c}}
{x = 2}\\
{y = t}
\end{array}\,\,\left( {t \in R} \right)} \right.\)
C.
\(\left\{ {\begin{array}{*{20}{c}}
{x = 3 + t}\\
{y = 1 + t}
\end{array}\,\,\left( {t \in R} \right)} \right.\)
D.
\(\left\{ {\begin{array}{*{20}{c}}
{x = t}\\
{y = 3 - t}
\end{array}\,\,\left( {t \in R} \right)} \right.\)
A. Song song
B. Cắt nhau
C. Vuông góc
D. Trùng nhau
A. \(\frac{5}{{\sqrt {13} }}\)
B. \(\frac{7}{{\sqrt {13} }}\)
C. \(\frac{12}{{\sqrt {13} }}\)
D. \(\frac{15}{{\sqrt {13} }}\)
A. \(1 + \sqrt 2 \)
B. \(\frac{{2 + \sqrt 2 }}{2}\)
C. \(\frac{{\sqrt 2 - 1}}{2}\)
D. \(\frac{{\sqrt 2 + 1}}{2}\)
A. \(\frac{{a\sqrt 3 }}{2}\)
B. \(\frac{{a\sqrt 3 }}{3}\)
C. \(\frac{{a\sqrt 2 }}{2}\)
D. \(\frac{{a\sqrt 2 }}{3}\)
A. \(4x + 2y + 3 = 0\)
B. \(4x + 2y - 3 = 0\)
C. \(4x + 2y - 8 = 0\)
D. \(4x + 2y + 8 = 0\)
A. \(\frac{1}{{\sqrt {17} }}\)
B. \(\frac{2}{{\sqrt {17} }}\)
C. \(-\frac{1}{{\sqrt {17} }}\)
D. \(-\frac{2}{{\sqrt {17} }}\)
A. \(\frac{{49}}{2}\)
B. 49
C. 10
D. 5
A. \(7x - y + 1 = 0\)
B. \(x - 7y + 1 = 0\)
C. \(x + 7y + 1 = 0\)
D. \(7x + y + 1 = 0\)
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