@options

@figure;
  gogeometry = texte( -13.8 , -4.3 ,"Antonio Gutierrez.     www.gogeometry.com")  { kaki , dec1 , car-3 };
  click = texte( -13.8 , -3.8 ,"Click the left button to start/stop the animation")  { rougefonce , dec2 , car-2 };
  hyp = texte( -14.8 , 5 ,"HYPOTESIS")  { rougefonce , dec2 , car-2 };
  explore = texte( -14.8 , 1 ,"TO EXPLORE:")  { rouge , dec2 , car-2 };
  explore1 = texte( -14.5 , 0.5 ,"1. Click the red button to start/stop animation")  { rougefonce , dec2 , car-2 };
  explore2 = texte( -14.5 , 0 ,"2. Activate the Step-by-Step construction bar:")  { rougefonce , dec2 , car-2 };
  explore2a = texte( -14.5 , -0.5 ,"    Press P and click the left mouse on any free area")  { rougefonce , dec2 , car-2 };
  explore3 = texte( -14.5 , -1 ,"3. Manipulate: Drag A, C, D, O, O1, O2, O3, O4")  { rougefonce , dec2 , car-2 };
  explore4 = texte( -14.5 , -1.5 ,"    at any step ")  { rougefonce , dec2 , car-2 };
  O = point( 3.33 , -0.13 )  { rouge };
  N = point( 2.93 , 2.47 )  { i };
  N1 = point( 3.47 , 1.57 )  { i };
  ceNN1 = cercle( N , N1 )  { i };
  xx = reel( 315 , 0 , 360 , 1 )  { oscille , (7.67,-8) , i };
  var yy = 180*cos(xx)+180 { 307.279220613579 };
  B = pointsur( ceNN1 , yy )  { rouge , rond2 , (-0.56,-0.77) };
  ciAB = cercle( O , B )  { rouge , 2 , plein10 };
  A = pointsur( ciAB , 139.34 )  { rouge , rond3 , (-0.5,-0.86) };
  C = pointsur( ciAB , 308.66 )  { rouge , rond3 };
  D = pointsur( ciAB , -96.93 )  { rouge , rond3 };
  hyp1 = texte( -14.5 , 4.5 ,"1. Draw concyclic points A,B,C,D")  { stop , rougefonce , dec2 , car-2 };
  medAB = mediatrice( A , B )  { i };
  O1 = pointsur( medAB , 3.62 )  { sansnom };
  centro1 = texte( O1 ,"Ģi(O,1)")  { vert , (-0.77,-0.2) , dec2 , car-2 };
  hyp2 = texte( -14.5 , 4 ,"2. Draw four circles through AB, BC, CD and AD")  { rougefonce , dec2 , car-2 };
  ciO1A = cercle( O1 , A )  { stop , vert , plein10 };
  medBC = mediatrice( B , C )  { i };
  O2 = pointsur( medBC , 3.36 )  { sansnom };
  centro2 = texte( O2 ,"Ģi(O,2)")  { vert , (0.25,-0.37) , dec2 , car-2 };
  ciO2B = cercle( O2 , B )  { stop , vert , plein10 };
  medCD = mediatrice( C , D )  { i };
  O3 = pointsur( medCD , 2 )  { sansnom };
  centro3 = texte( O3 ,"Ģi(O,3)")  { vert , (-0.03,-0.27) , dec2 , car-2 };
  ciO3C = cercle( O3 , C )  { stop , vert , plein10 };
  medAD = mediatrice( A , D )  { i };
  O4 = pointsur( medAD , -2 )  { sansnom };
  centro4 = texte( O4 ,"Ģi(O,4)")  { vert , (-1.13,-0.3) , dec2 , car-2 };
  ciO4D = cercle( O4 , D )  { stop , vert , plein10 };
  hyp3 = texte( -14.5 , 3.5 ,"3. Draw intersections A',B',C',D'")  { rougefonce , dec2 , car-2 };
  A' = intersection( ciO1A , ciO4D , A )  { stop , rond3 , (-1,-0.43) };
  B' = intersection( ciO1A , ciO2B , B )  { stop , rond3 , (0.1,-0.8) };
  C' = intersection( ciO2B , ciO3C , C )  { stop , rond3 , (0.13,0) };
  D' = intersection( ciO3C , ciO4D , D )  { stop , rond3 , (-0.5,0.03) };
  medA'B' = mediatrice( A' , B' )  { i };
  medA'D' = mediatrice( A' , D' )  { i };
  O' = intersection( medA'B' , medA'D' )  { (0,-0.53) };
  conc = texte( -14.8 , 2.5 ,"CONCLUSION TO PROVE:")  { rougefonce , dec2 , car-2 };
  conc1 = texte( -14.5 , 2 ,"1. A',B',C',D' are concyclic")  { rougefonce , dec2 , car-2 };
  ciO'A' = cercle( O' , A' )  { stop , 2 , plein10 };

@config;
boutons=animation;