bonjour
[EF]² = ( 1 - 2 )² + ( - 4 - 1 )² = ( - 1 )² + ( - 5 )² = 1 + 25 = 26
[ FG]² = ( - 4 - 1 )² + ( - 5 + 4 )² = ( - 5 )² + ( - 1 )² = 26
[ GH]² = ( - 3 + 4 )² + ( 0 + 5 )² = 1² + 5 ² = 26
[ EH]² = ( - 3 - 2 )² + ( 0 - 1 )² = ( - 5 )² + ( - 1 )² = 26
c'est un carré