Time period is \(12 \,s\) from diagram.

\(\omega=\frac{2 \pi}{12}=\frac{\pi}{6}\)

Amplitude \(A=4\)

Initial phase is determined by putting known values in the equation.

\(2=4 \sin \left(\frac{\pi}{6} t+\phi\right)\)

\(\sin ^{-1} \frac{1}{2}=\phi[t=0]\)

\(\frac{\pi}{6}=\phi\)

Hence equation is \(x=\left(\frac{\pi}{6} t+\frac{\pi}{6}\right)\)