@options;

@figure;
  A = point( -3.1 , 3.17 );
  B = point( 2.73 , 3.4 );
  sAB = segment( A , B )  { 2 };
  perpBsAB = perpendiculaire( B , sAB );
  C = pointsur( perpBsAB , -5.5 );
  perpCperpBsAB = perpendiculaire( C , perpBsAB );
  perpAperpCperpBsAB = perpendiculaire( A , perpCperpBsAB );
  D = intersection( perpAperpCperpBsAB , perpCperpBsAB );
  polyABCD = polygone( A , B , C , D  )  { 2 };
  I = milieu( sAB );
  J = milieu( D , C );
  sIJ = segment( I , J );
  polyIBCJ = polygone( I , B , C , J  )  { orange , 3 };
  sIJ1 = segment( I , J );

@analyse;
calc(AB/IJ) = 1.06
calc(BC/IB) = 1.89