Can any one help me with these equations. And help me to graph it too.
Um, both equations are the same so what do you want done with them?
As for the graphing, what does the graph of
$\displaystyle r_{xy}(t) = a~cos(t) \hat{i} + a~sin(t) \hat{j}$
the projection of the graph of r(t) onto the xy plane, look like? What does the $\displaystyle t \hat{k}$ do to this graph?
-Dan