@options; @figure; A = point( -5.5 , -2.65 ) { (-0.37,-0.02) }; B = point( 5 , -4.01 ); C = point( -1.1 , 4.53 ) { (-0.02,-0.67) }; sAB = segment( A , B ); sBC = segment( B , C ); sCA = segment( C , A ); angleBAC = angle( B , A , C ) { rouge , plein50 }; angleCBA = angle( C , B , A ) { vert , plein50 }; angleACB = angle( A , C , B ) { plein50 }; E = milieu( sCA ) { (-0.43,-0.67) }; F = milieu( sBC ) { (0.08,-0.63) }; sEF = segment( E , F ) { noir }; s = reflexion( sEF ); C' = image( s , C ) { noir , (-0.04,0.08) }; H = projete( E , sAB ) { (-0.21,0.03) }; D = projete( F , sAB ); sEH = segment( E , H ) { noir }; sFD = segment( F , D ) { noir }; angleC'HE = angle( C' , H , E ); angleC'DF = angle( C' , D , F ); sEC' = segment( E , C' ) { rouge }; sFC' = segment( F , C' ); angleEC'A = angle( E , C' , A ) { rouge , plein50 }; angleDC'F = angle( D , C' , F ) { vert , plein50 }; angleFC'E = angle( F , C' , E ) { plein50 }; sFB = segment( F , B ) { vertfonce }; sEA = segment( E , A ) { rouge };