Polar Plot

\usepackage{pgfplots}
\pgfplotsset{compat=1.17}

\usepgfplotslibrary{polar}

\begin{tikzpicture}
  \begin{polaraxis}[
    width=6cm,
    xlabel={$\theta$},
    ylabel={$r$}
  ]
    \addplot[domain=0:360, samples=73, thick] {sin(4*x)};
  \end{polaraxis}
\end{tikzpicture}