$$Find the $($a$)$ amplitude, $($b$)$ wavelength, $($c$)$ period, and $($d$)$ speed of a wave whose displacement is given by y $=1\mathrm{.}3$ cos $(0\mathrm{.}69$x $+31$t$),$ where x and y are in centimeters and t in seconds. $($e$)$ In which direction is the wave propagating?