Manipulate[Show[ParametricPlot[{ax Cos[t1],ay Cos[t1-fi]},{t1,0,2 Pi},PlotRange->1.1,PlotStyle->Dashed
],Graphics[{Thick,Arrow[{{0,0},{ax Cos[t2],ay Cos[t2-fi]}}]/.{t2->t3}}]],{{t3,0,"t"},0,2 Pi,Pi/100.},{{ax,1,"Ax"},0,1,.05},{{ay,0,"Ay"},0,1,.05},{fi,0,2. Pi,Pi/12},ControlPlacement->Left]