\input{preamble-standalone.ltx}
\begin{document}

% Ex. No. 23 (Section  7.7 : Demi-tangentes Courbe de Lorentz )

\begin{tikzpicture}[scale=1.25]
  \tkzInit[xmax=1,ymax=1,xstep=0.1,ystep=0.1]
  \tkzGrid(0,0)(1,1)
  \tkzAxeXY
  \tkzFct[color = red,thick, domain =0:1]{(exp(\x)-1)/(exp(1)-1)}
  \tkzSetUpPoint[size=6]
  \tkzDrawTangentLine[draw, kl = 0,  kr = 0.4](0)
  \tkzDrawTangentLine[draw, kl = 0.4,kr = 0  ](1)
  \tkzText[draw,color = red,fill = orange!20](0.5,0.6)%
          {$f(x)=\dfrac{\text{e}^x-1}{\text{e}-1}$}
\end{tikzpicture}

\end{document}
