@options;

@figure;
  A = point( 1.9 , 4 )  { (-0.2,-0.8) };
  B = point( 8.27 , -1.77 );
  sAB = segment( A , B )  { 2 };
  C = point( -8.03 , -4.53 )  { (-0.73,-0.07) };
  sBC = segment( B , C )  { 2 };
  sCA = segment( C , A )  { 2 };
  medsBC = mediatrice( sBC )  { sansnom };
  medsCA = mediatrice( sCA )  { sansnom };
  medsAB = mediatrice( sAB )  { sansnom };
  O = intersection( medsAB , medsCA )  { rond2 };
  ceOA = cercle( O , A );
  I = milieu( sBC );
  J = milieu( sCA );
  K = milieu( sAB );
  sAI = segment( A , I )  { rouge };
  sBJ = segment( B , J )  { rouge };
  sCK = segment( C , K )  { rouge };
  G = intersection( sAI , sCK )  { rouge , rond2 };
  perpAsBC = perpendiculaire( A , sBC )  { vert , sansnom };
  perpBsCA = perpendiculaire( B , sCA )  { vert , sansnom };
  perpCsAB = perpendiculaire( C , sAB )  { vert , sansnom };
  H = intersection( perpCsAB , perpBsCA )  { vert , rond2 };
  bissCAB = bissectrice( C , A , B )  { orange , sansnom };
  bissABC = bissectrice( A , B , C )  { orange , sansnom };
  bissBCA = bissectrice( B , C , A )  { orange , sansnom };
  S = intersection( bissABC , bissBCA )  { orange , rond2 };
  S1 = projete( S , sBC )  { orange };
  S2 = projete( S , sCA )  { orange };
  S3 = projete( S , sAB )  { orange };
  ceSS2 = cercle( S , S2 )  { orange };