Plotting polar curves

We first need to load a graphics package...

<< Graphics`

...and we're good to go. Say we want to plot the polar curve r(t), a≤t≤b...

r = Sin[4 t];
a = 0;
b = 2 Pi;

...here is the Mathematica command that does it:

PolarPlot[r, {t, a, b}]