Bài tập 25 trang 205 SGK Toán 10 NC

\(\begin{array}{*{20}{l}}
\begin{array}{l}
*\cos \left( {\alpha  - \frac{{3\pi }}{2}} \right) = \cos \left( {\frac{{3\pi }}{2} - \alpha } \right)\\
 = \cos \left( {\pi  + \frac{\pi }{2} - \alpha } \right)\\
 =  - \cos \left( {\frac{\pi }{2} - \alpha } \right) =  - \sin \alpha 
\end{array}\\
\begin{array}{l}
*\sin \left( {\alpha  - \frac{{3\pi }}{2}} \right) = \sin \left( {\frac{{3\pi }}{2} - \alpha } \right)\\
 =  - \sin \left( {\pi  + \frac{\pi }{2} - \alpha } \right)\\
 = \sin \left( {\frac{\pi }{2} - \alpha } \right) = \cos \alpha 
\end{array}\\
\begin{array}{l}
*\tan \left( {\alpha  - \frac{{3\pi }}{2}} \right) =  - \cot \alpha \\
\left( {\alpha  \ne k\pi ;k \in Z} \right)
\end{array}\\
\begin{array}{l}
*\cot \left( {\alpha  - \frac{{3\pi }}{2}} \right) =  - \tan \alpha \\
\left( {\alpha  \ne \frac{\pi }{2} + k\pi ;k \in Z} \right)
\end{array}
\end{array}\)

-- Mod Toán 10 HỌC247