Draw three bisectors from the three vertices of a triangle

Question

(1). Two bisectors must be drawn from the two vertices A and B so that they intersect at P. (2). BUT the other bisector drawn from the vertex C must be terminated before intersecting P.

    \documentclass[11pt,a4paper]{article}
    \usepackage{blindtext}
    \usepackage{tikz}
    \usepackage{tkz-euclide}
    \usetkzobj{all}
    \usepackage{color}

 \begin{document}
 \normalsize{\textbf{Theorem 1.24.} \textit{The bisectors of the angles of a triangle meet in a point which is equally distant from the sides.}}
\begin{center}
\begin{tikzpicture}
\tkzDefPoint(0,0){A}
\tkzDefPoint(12,0){B}
\tkzLabelPoints[below](A)
\tkzLabelPoints[below](B)
\tkzDrawSegment(A,B)
\tkzDefPoint(6,7){C}
\tkzLabelPoints[above](C)
\tkzDrawSegment(A,C)
\tkzDrawSegment(B,C)
\end{tikzpicture}
\end{center}
\end{document}

Answer 1

\documentclass[11pt,a4paper]{article}
\usepackage{blindtext}
\usepackage{tikz}
\usepackage{tkz-euclide}
\usetkzobj{all}
\usepackage{color}

\begin{document}

\normalsize{\textbf{Theorem 1.24.} \textit{The bisectors of the angles of a triangle meet in a point which is equally distant from the sides.}}
\begin{center}
\begin{tikzpicture}
\tkzDefPoint(0,0){A}
\tkzDefPoint(12,0){B}
\tkzLabelPoints[below](A)
\tkzLabelPoints[below](B)
\tkzDrawSegment(A,B)
\tkzDefPoint(6,7){C}
\tkzLabelPoints[above](C)
\tkzDrawSegment(A,C)
\tkzDrawSegment(B,C)

\tkzDefLine[bisector](C,B,A)
\tkzGetPoint{i}
\tkzDefLine[bisector](B,A,C)
\tkzGetPoint{j}
\tkzInterLL(A,j)(B,i) 
\tkzGetPoint{P}
\tkzLabelPoints[below](P)
\tkzDrawBisector(C,B,A)(P)
\tkzDrawBisector(C,A,B)(Q)
\tkzDrawSegment[add=0pt and -30pt](C,P)
\end{tikzpicture}
\end{center}

\end{document}

Remarks:

• Change -30pt in

  \tkzDrawSegment[add=0pt and -30pt](C,P)
  

  to get the desired shortening for the segment from C to P.

• Instead of the manual markup for your theorems, you should consider using a dedicated package such as amsthm or ntheorem: A little example with amsthm:

  \documentclass[11pt,a4paper]{article}
  \usepackage{blindtext}
  \usepackage{tikz}
  \usepackage{tkz-euclide}
  \usetkzobj{all}
  \usepackage{color}
  \usepackage{amsthm}
  
  \newtheorem{theo}{Theorem}
  
  \begin{document}
  
  \begin{theo}
  The bisectors of the angles of a triangle meet in a point which is equally distant from the sides.
  \end{theo}
  \begin{center}
  \begin{tikzpicture}
  \tkzDefPoint(0,0){A}
  \tkzDefPoint(12,0){B}
  \tkzLabelPoints[below](A)
  \tkzLabelPoints[below](B)
  \tkzDrawSegment(A,B)
  \tkzDefPoint(6,7){C}
  \tkzLabelPoints[above](C)
  \tkzDrawSegment(A,C)
  \tkzDrawSegment(B,C)
  
  \tkzDefLine[bisector](C,B,A)
  \tkzGetPoint{i}
  \tkzDefLine[bisector](B,A,C)
  \tkzGetPoint{j}
  \tkzInterLL(A,j)(B,i) 
  \tkzGetPoint{P}
  \tkzLabelPoints[below](P)
  \tkzDrawBisector(C,B,A)(P)
  \tkzDrawBisector(C,A,B)(Q)
  \tkzDrawSegment[add=0pt and -30pt](C,P)
  \end{tikzpicture}
  \end{center}
  
  \end{document}