@options;

@figure;
  A = point( -4 , 0.23 );
  B = point( 1.63 , 0.7 );
  sAB = segment( A , B );
  C = point( -2.07 , 5.7 );
  sBC = segment( B , C );
  sCA = segment( C , A );
  perpCsAB = perpendiculaire( C , sAB )  { orange };
  perpBsCA = perpendiculaire( B , sCA )  { orange };
  H = intersection( perpBsCA , perpCsAB )  { vertfonce };