(AB)² = ( 3 - 4 )² + ( - 1 - 2 )² = ( - 1 )² + ( - 3 )² = 1 + 9 = 10
( AM)² = ( 1 - 4 )² + ( 1 - 2 )² = ( - 3 )² + ( - 1 )² = 9 + 1 = 10
( MB)² = ( - 3 - 1 )² + ( - 1 - 1 )² = ( - 4 )² + ( - 2 )² = 16 + 4 = 20
10 + 10 = 20
on a un triangle rectangle isocèle