Label & Marks: tkz library

• Segment:
  • Label:
    \tkzLabelSegment[pos=0.5,left](P1,P2) {$l_{12}$};
  • Mark:
    \tkzMarkSegment[size=0.5,mark=|](P1,P2);
• Angle:
  • Label:
    \tkzLabelAngle[pos=0.9](P1,P2,P3) {$l_{12}$};
  • Mark:
    \tkzMarkAngle[size=0.5,mark=||](P1,P2,P3);