Plot[x^2,{x,-5,5}]

Plot[theta^2,{theta,-5,5}]

PolarPlot[theta^2,{theta,-5,5}]

PolarPlot[{8Cos[theta],Sin[theta]},{theta,0,2Pi}]

PolarPlot[{1+Cos[3theta]},{theta,0,2Pi}]

PolarPlot[{Cos[4theta/3]},{theta,0,2Pi}]

Manipulate[PolarPlot[{Cos[4theta/3]},{theta,0,end}],{end,0.001,10Pi}]

PolarPlot[{Cos[4theta/3]},{theta,0,6Pi}]