Câu hỏi:

\(S = \frac{1}{2}bc{\rm{sin}}A.\)

\(S = \frac{1}{2}bc{\rm{sin}}B.\)

\(S = C\frac{1}{2}bc{\rm{sin}}C.\)

\(S = \frac{1}{2}ac{\rm{sin}}A.\)

\({\rm{sin}}{0^ \circ } + {\rm{cos}}{0^ \circ } = 0\)

\({\rm{sin}}{180^ \circ } + {\rm{cos}}{180^ \circ } = - 1\)

\({\rm{sin}}{90^ \circ } + {\rm{cos}}{90^ \circ } = 1\)

\({\rm{sin}}{60^ \circ } + {\rm{cos}}{60^ \circ } = \frac{{\sqrt 3 + 1}}{2}\)

\(\left( {0;1} \right).\)

\(\left( { - 1;1} \right).\)

\(\left( { - 3;0} \right).\)

\(\left( { - 3;1} \right).\)

\(3{x^2} + 2y \le 5\)

\(2x - 5y + z \le 0\)

\(3x < 2y - 4\)

\({x^2} + 3x > \frac{1}{3}\)

\(M = \left( { - \infty ;9} \right)\)

\(M = \left[ { - \infty ;9} \right)\)

\(M = \left( { - \infty ;9} \right]\)

\(M = \left( {9; + \infty } \right)\)

\(3 \subset \mathbb{N}\)

\(3 \in \mathbb{N}\)

\(3 \le \mathbb{N}\)

\(3 < \mathbb{N}\)

\(\bar P:\) " \(\sqrt 2 \ne 2\) "

\(\bar P:\) " \(\sqrt 2 < 2\) "

\(\bar P:\) " \(\sqrt 2 > 2\) "

\(\bar P:\) " \(\sqrt 2 \ge 2\) "

\(a = 2R{\rm{tan}}A\)

\(a = R{\rm{sin}}A\)

\(a = 2R{\rm{sin}}A\)

\(a = 2R{\rm{cos}}A\)

\(\frac{2}{{\sqrt 3 }}\)

\(\frac{{1 + \sqrt 3 }}{3}\)

2

\(\frac{4}{{\sqrt 3 }}\)

a

\(\left( {\sqrt 2 - 1} \right)a\)

\(\frac{{\sqrt 2 }}{2}a\)

\(\frac{1}{2}a\)