Complete the steps to derive the cofunction identity:
$\begin{aligned}
\sin \left(\frac{\pi}{2}-x\right) & = [\quad] \left(\frac{\pi}{2}\right) \cos (x) - [\quad] \left(\frac{\pi}{2}\right) \sin (x) \\
& = (\quad) \cos (x) - (\quad) \sin (x) \\
& = (\quad)(x)
\end{aligned}$
$\begin{aligned}
\sin \left(\frac{\pi}{2}-x\right) & = [\quad] \left(\frac{\pi}{2}\right) \cos (x) - [\quad] \left(\frac{\pi}{2}\right) \sin (x) \\
& = (\quad) \cos (x) - (\quad) \sin (x) \\
& = (\quad)(x)
\end{aligned}$