Bonjour,
1)
Aire totale:
(7+x) ( x+4) =
7x +28 +x² +4x
= x² +11x +28
Aire carré: x*x = x²
aire colorée:
x² +11x +28 - x² = (11x+28) cm²
2)
DE +EF+FG +GB+BCV +DC
DE = BC-AE
DC= 7+x
4 +x+ x+ 7+ x+4 + 7+x =
( 4x + 15 )cm
