$12\mathrm{.}3$ Express each of the waveforms in Fig. P$12\mathrm{.}3($on page $667)$ in terms of step functions and then determine its Laplace transform. $[$Recall that the ramp function is related to the step function by r$($t $$ T$)=($t $$ T$)$ u$($t $$ T$).]$ Assume that all waveforms are zero for t $<0.$