\(x=2 \sin \omega t+4 \cos \omega t\)

It can also be written as

\(x=\sqrt{2^2+4^2}\left(\frac{2}{\sqrt{2^2+4^2}} \sin \omega t \frac{4}{\sqrt{2^2+4^2}} \cos \omega t\right)\)

\(x=\sqrt{20} \sin (\omega t+\phi)\)

\(\sqrt{20}=\text { Amplitude }\)

\(\text { or Amplitude }=2 \sqrt{5}\)