LaTeX-examples/tikz/thales-circle-triangle/thales-circle-triangle.tex

\documentclass{article}
\usepackage[pdftex,active,tightpage]{preview}
\setlength\PreviewBorder{2mm}
\usepackage{tikz}
\usepackage{tkz-euclide}
\usetkzobj{all}
\usetikzlibrary{shapes, calc, decorations}
\usepackage{amsmath,amssymb}
\usepackage{helvet}
\usepackage[eulergreek]{sansmath}

\begin{document}
\begin{preview}
\begin{tikzpicture}[scale=1.5,font=\sansmath\sffamily]
    \tkzDefPoint(0,0){A}
    \tkzDefPoint(4,0){B}
    \tkzDefPoint(2,0){M}
    \tkzDefPoint(3,2){H}

    \tkzInterLC[/tikz/overlay](M,H)(M,B) \tkzGetPoints{E}{C}

    \tkzLabelPoints[above right](C)

    % Draw polygon
    \tkzDrawPolygon[rounded corners=0.1mm, fill=gray!2](A,B,C)

    \tkzMarkAngle[arc=l,fill=green!30,size=0.6cm](C,B,A)
    \tkzLabelAngle[pos=0.4](A,B,C){$\beta$}

    \tkzMarkAngle[fill=green!30,size=0.6cm](M,C,B)
    \tkzLabelAngle[pos=0.4](B,C,M){$\beta$}

    \tkzMarkAngle[fill=green!30,size=0.6cm](B,M,C)
    \tkzLabelAngle[pos=0.4](B,M,C){$\delta$}

    \tkzMarkAngle[fill=green!30,size=0.6cm](M,A,C)
    \tkzLabelAngle[pos=0.4](M,A,C){$\alpha$}

    \tkzMarkAngle[fill=green!30,size=0.6cm](A,C,M)
    \tkzLabelAngle[pos=0.4](A,C,M){$\alpha$}

    \tkzMarkAngle[fill=green!30,size=0.6cm](C,M,A)
    \tkzLabelAngle[pos=0.3](C,M,A){$\gamma$}

    \tkzDrawSector[thick](M,B)(A)

    \tkzLabelSegment[below=-1pt](A,M){$r$}
    \tkzLabelSegment[below=-1pt](M,B){$r$}
    \tkzLabelSegment[right=-1pt](M,C){$r$}

    \tkzLabelPoints[below left](A)
    \tkzLabelPoints[below right](B)
    \tkzLabelPoints[below](M)

    \tkzDrawSegments(A,B B,C C,A)
    \tkzDrawSegments(M,B B,C C,M)
\end{tikzpicture}
\end{preview}
\end{document}