# How to illustrate sin, cos, and tan on a unit circle with TikZ?

As a beginner in tikz, I don't know how to draw this picture in LaTeX with TikZ. Please show me how to draw it. • If you read the introduction of the TikZ manual you will find a very very very similar drawing. – Manuel Sep 26 '15 at 17:34

## 1 Answer

Here's one option:

\documentclass[border=5pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{angles,quotes}

\newcommand\Base{
\begin{scope}[xshift=#1]
\clip
(-0.5,5.5) rectangle (5.5,-0.5);
\draw[->]
(-0.5,0) -- (5,0) node[right] {$u$};
\draw[->]
(0,-0.5) -- (0,5) node[above] {$v$};
\coordinate (O) at (0,0);
\coordinate (aux1) at (40:4);
\coordinate (aux2) at (aux1|-0,0);
\coordinate (aux3) at (4,{4*tan(40)});
\draw
(O) -- (aux3) -- (aux3|-0,0)
(aux1) -- (aux2);
\draw[thick,red!70!black]
(O) circle (4);
\pic[draw,"$x$",angle radius=30pt,angle eccentricity=1.2] {angle = aux2--O--aux1};
\end{scope}
}

\begin{document}

\begin{tikzpicture}[>=latex]
\Base
\filldraw[thick,draw=blue,fill=blue!40,fill opacity=0.3,text opacity=1]
(O) -- (aux1) -- node[left] {$\sin x$} (aux2)  -- node[below] {$\cos x$} cycle;

\Base[6.3cm]
\filldraw[thick,draw=blue,fill=blue!40,fill opacity=0.3,text opacity=1]
(O) -- (aux1) arc (40:0:4) -- node[below] {$1$} cycle;

\Base[12.6cm]
\filldraw[thick,draw=blue,fill=blue!40,fill opacity=0.3,text opacity=1]
(O) -- (aux3) -- node[right] {$\tan x$} (aux3|-0,0)  -- node[below] {$1$} cycle;

\end{tikzpicture}

\end{document} 