@options;
  repereortho(310,270,30,1,1){ 0 , moyen , noir , num1 ,i};

@figure;
  O = point( -2.37 , 0 );
  cerayO4 = cerclerayon( O , 4 );
  H = pointsur( cerayO4 , 99.95 )  { noir , rond2 , (-0.6,-0.97) };
  sOH = segment( O , H );
  d = perpendiculaire( H , sOH )  { noir , q2 };
  P = pointsur( d , 2.82 )  { rouge , rond2 , (-0.17,0.37) };
  var x =OP { 4.8942963332188 };
  texte1 = texte( -4.9 , 6.5 ,"OP = $x$")  { noir , dec6 };
  Q = pointsur( cerayO4 , 344.46 )  { sansnom };
  vOQ = vecteur( O , Q );
  vQO = vecteur( Q , O );
  I = milieu( O , Q )  { i };
  texte2 = texte( I ,"4")  { dec2 };
  sOP = segment( O , P )  { rouge };