TikZ unit circle

unit_circle.tex

% Begin figure (this isn't important for the graphic, but allows it to be easily embedded)
\begin{figure}
%    \centering

\begin{tikzpicture}[scale=3]
    \draw[step=.5cm,black!30!white,very thin] (-1.4,-1.4) grid (1.4,1.4);
    \filldraw[fill=green!30,draw=green!40!black] (0,0) -- (3mm,0mm)
    arc [start angle=0, end angle=30, radius=3mm] -- cycle;
    \node[green!40!black] at (15:2mm) {$\alpha$};
    \draw[->] (-1.5,0) -- (1.5,0) coordinate (x axis)node[right]{$x$};
    \draw[->] (0,-1.5) -- (0,1.5) coordinate (y axis)node[above]{$y$};
    \draw (0,0) circle [radius=1cm];
    \draw[very thick,orange]
    (30:1cm) -- node[left=1pt,fill=white] {$\sin \alpha$} (30:1cm |- x axis);
    \draw[very thick,blue]
    (30:1cm |- x axis) -- node[below=2pt,fill=white] {$\cos \alpha$} (0,0);
    \path [name path=upward line] (1,0) -- (1,1);
    \path [name path=sloped line] (0,0) -- (30:1.5cm);
    \draw [name intersections={of=upward line and sloped line, by=t}]
    [very thick,red] (1,0) -- node [right=1pt,fill=white]
    {$\displaystyle \tan \alpha$} (t);
    \draw (0,0) -- (t);
    
    \foreach \x/\xtext in {-1, -0.5/-\frac{1}{2}, 1}
    \draw (\x cm,1pt) -- (\x cm,-1pt) node[anchor=north,fill=white] {$\xtext$};
    \foreach \y/\ytext in {-1, -0.5/-\frac{1}{2}, 0.5/\frac{1}{2}, 1}
    \draw (1pt,\y cm) -- (-1pt,\y cm) node[anchor=east,fill=white] {$\ytext$};
\end{tikzpicture}
\caption{Unit circle in TikZ}

\label{fig:unit-circle}
\end{figure}