[tex]\bf \textit{Double Angle Identities}
\\ \quad \\
sin(2\alpha)=2sin(\alpha)cos(\alpha)
\\ \quad \\
\boxed{cos(2\alpha)=
\begin{cases}
cos^2(\alpha)-sin^2(\alpha)\\
1-2sin^2(\alpha)\\
2cos^2(\alpha)-1
\end{cases}}
\\ \quad \\
tan(2\alpha)=\cfrac{2tan(\alpha)}{1-tan^2(\alpha)}[/tex]
