Bentuk Relasi Sudut

LHS

\begin{equation*}
\begin{split}
& \sin x \cos(90 - x) + \cos x \sin(90 - x) \\\\
& \sin x \:.\: \sin x + \cos x \:.\: \cos x \\\\
& \sin^2 x + \cos^2 x \\\\
& 1
\end{split}
\end{equation*}

LHS = RHS