\documentclass[varwidth=true, border=2pt]{standalone} \usepackage{tkz-euclide} \usepackage{tikz} \usetikzlibrary{patterns} \begin{document} \usetkzobj{all} \begin{tikzpicture} \tkzSetUpPoint[shape=circle,size=10,color=black,fill=black] \tkzSetUpLine[line width=1] \tkzDefPoints{0/0/A, 4/0/B, -2/3/C} \tkzDefLine[orthogonal=through C,/tikz/overlay](A,B) \tkzGetPoint{helper} \tkzInterLL(A,B)(C,helper) \tkzGetPoint{Lc} %\tkzMarkAngle[arc=l,size=0.4cm,color=red,fill=red!20](A,La,B) %\tkzLabelAngle[pos=0.25](A,La,B){$\cdot$} \tkzDrawPolygon(A,B,C) \node at ($(A)+(-0.47,-0.2)$){$A$}; \node at ($(B)+(0.35,-0.2)$) {$B$}; % \tkzLabelPoint[below](B){$B$} is not accurate enough \node at ($(C)+(0.05,0.3)$) {$C$}; \node[green] at ($(Lc)+(-0.4,-0.1)$) {$L_C$}; \tkzDrawSegments[red](C,Lc) \tkzDrawSegments[blue](A,B) \tkzDrawSegments[dashed](Lc,A) \tkzLabelSegment[right,red](C,Lc){$h_c$} \tkzLabelSegment[above,blue](A,B){$c$} \tkzDrawPoints(A,B,C) \tkzDrawPoints[color=green,fill=green](Lc) \end{tikzpicture} \end{document}