Câu hỏi:

\({\rm{tan}}\left( {{{90}^ \circ } - \alpha } \right) = - {\rm{cot}}\alpha \)

\({\rm{cot}}\left( {{{90}^ \circ } - \alpha } \right) = - {\rm{tan}}\alpha \)

\({\rm{sin}}\left( {{{90}^ \circ } - \alpha } \right) = - {\rm{cos}}\alpha \)

\({\rm{cos}}\left( {{{90}^ \circ } - \alpha } \right) = {\rm{sin}}\alpha \)

\(\left( {1;5} \right)\)

\(\left( {2;0} \right)\)

\(\left( {1;2} \right)\)

\(\left( {0;\frac{1}{2}} \right)\)

\(\sqrt 3 \)

2

1

0

\(24c{m^2}\)

\(10c{m^2}\)

\(12c{m^2}\)

\(48c{m^2}\)

"\(\exists \,x \in \mathbb{R}\,|\,{x^2} - x + 3 \ge 0\)"

" \(\forall \,x \notin \mathbb{R}\,|\,{x^2} - x + 3 \ge 0\)"

"\(\exists \,x \in \mathbb{R}\,|{x^2} - x + 3 > 0\)"

" \(\forall \,x \in \mathbb{R}\,|{x^2} - x + 3 > 0\)"

\(3x - 5y + 7z \le 0\)

\(21x + 23y < 25\)

\(15{x^2} + 17x - 19 > 0\)

\(9{x^2} + 11y > 13\)

\(\overrightarrow {BP} \)

\(\overrightarrow {AC} \)

\(\overrightarrow {CM} \)

\(\overrightarrow {AN} \)

\(\left\{ {1;3;5;7;8;9} \right\}\)

\(\left\{ {1;3;5} \right\}\)

\(\left\{ {3;5} \right\}\)

\(\left\{ {1;7;9} \right\}\)

\(\overrightarrow {OA} = \overrightarrow {OC} \)

\(\overrightarrow {OB} = \overrightarrow {OD} \)

\(\overrightarrow {AD} = \overrightarrow {CB} \)

\(\overrightarrow {AB} = \overrightarrow {DC} \)