a) Cho \(a - b = \frac{{2\pi }}{3}\). Tính giá trị \(P = {\left( {\sin a + \sin b} \right)^2} + {\left( {\cos a + \cos b} \right)^2}\)
b) Rút gọn biểu thức \(Q = \frac{{\sin \left( {x + y} \right) + \sin \left( {x - y} \right)}}{{\cos \left( {x + y} \right) - \cos \left( {x - y} \right)}}\)
c) Chứng minh \({\tan ^2}x + {\cot ^2}x = \frac{{6 + 2\cos 4x}}{{1 - \cos 4x}}\)
A.\(\begin{array}{l}{\rm{a)}}\,\,P = 0\\{\rm{b)}}\,\,Q = \cot y\end{array}\)
B.\(\begin{array}{l}{\rm{a)}}\,\,P = 1\\{\rm{b)}}\,\,Q = - \cot y\end{array}\)
C.\(\begin{array}{l}{\rm{a)}}\,\,P = 2\\{\rm{b)}}\,\,Q = \tan y\end{array}\)
D.\(\begin{array}{l}{\rm{a)}}\,\,P = - 1\\{\rm{b)}}\,\,Q = - \tan y\end{array}\)
b) Rút gọn biểu thức \(Q = \frac{{\sin \left( {x + y} \right) + \sin \left( {x - y} \right)}}{{\cos \left( {x + y} \right) - \cos \left( {x - y} \right)}}\)
c) Chứng minh \({\tan ^2}x + {\cot ^2}x = \frac{{6 + 2\cos 4x}}{{1 - \cos 4x}}\)
A.\(\begin{array}{l}{\rm{a)}}\,\,P = 0\\{\rm{b)}}\,\,Q = \cot y\end{array}\)
B.\(\begin{array}{l}{\rm{a)}}\,\,P = 1\\{\rm{b)}}\,\,Q = - \cot y\end{array}\)
C.\(\begin{array}{l}{\rm{a)}}\,\,P = 2\\{\rm{b)}}\,\,Q = \tan y\end{array}\)
D.\(\begin{array}{l}{\rm{a)}}\,\,P = - 1\\{\rm{b)}}\,\,Q = - \tan y\end{array}\)
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Hóa Học lớp 12
