$12.$ A transverse wave on a string is given by $(,)=(0\mathrm{.}2$ m$)*$cos$(6\mathrm{.}28$ m$1*$x $1\mathrm{.}57$ s$1*$t$).$ Find the amplitude and wavelength of the wave.

a$)$ Amplitude $1$ m$,$ wavelength $0\mathrm{.}2$ m$$ b$)$ Amplitude $0\mathrm{.}2$ m$,$ wavelength $1$ m$$ c$)$ Amplitude $0\mathrm{.}2$ m$,$ wavelength $6\mathrm{.}28$ m$$ d$)$ none of these.