\psset{CodeFig=true, PointSymbol=none}
\pstTriangle[PosAngleA=180]
        (-1,0){A}(3,-1){B}(3,2){C}
\pstProjection[PosAngle=-90]{B}{A}{C}
\pstProjection{B}{C}{A}
\pstProjection[PosAngle=90]{A}{C}{B}
\pstInterLL[PosAngle=135,PointSymbol=square]
  {A}{A'}{B}{B'}{H}