At time `t` the bottommost poit will rotate and angle `theta=omegat` with respect to the centre of the disc C. The centre C will travel a distance `s=vt`.
In the figure, `PQ=Rsintheta=Rsinomegat` and `CQ=Rcostheta=Rcosomegat`
coordinates of point P at time t are `x=OM-PQ=vt-Rsinomegat`
and `y=CM-PQ=R-Rcosomegat`
`therefore(x,y)=(vt-Rsinomegat,R-Rcosomegat)`