In[34]:=solNDSolvex''txt y't^2xt19.8,y''t2xt x't y't9.8 ytxt,x0x'0y0y'01, xt, yt, t, 0, 20Out[34]= xtInterpolatingFunction0., 20., t,ytInterpolatingFunction0., 20., tIn[35]:= ParametricPlotEvaluatext Sinyt, xt Cosyt . sol,t, 0, 20, PlotRangeAllOut[35]=4 2 2 45101520