bonjour pouvez vous m'aidez svp merciiiii

Bonjour,

1) Sur la figure, x = BH = AD, donc il faut que x ≥ 3 car :

AD = BC = BG + GC et GC = 3

Donc :
x = 2 non
x = 5 oui
x = 9 oui
x = 12 non car il faut x ≤ AB donc x ≤ 12

2) AH = 12 - x = 12 - 5 = 7 cm

et AD = x = 5 cm

Donc P = 2 x (7 + 5) = 24 cm

et A = 7 x 5 = 35 cm²

3)

BC = AD = x

AH = AB - HB = DC - HB = 12 - x

CG = CB - GB = AD - GB = x - 3

4)

P(ABCD) = 2(AB + AD) = 2(12 + x)

A(ABCD) = AB x AD = 12x

P(EFCG) = 2(EF + EC) = 2[(x - 3) + x] = 2(2x - 3)

A(EFCG) = EF x EC = x(x - 3)

P(ABGFED) = AB + BG + GF + FE + ED + DA

= 12 + 3 + x + (x - 3) + (12 - x) + x

= 24 + 2x

A(ABGFED) = A(ABCD) - A(EFCG)

= 2(12 + x) - x(x - 3)

= 24 + 2x - x² + 3x

= -x² + 5x + 24

5) A = -(x - 8)(x + 3)

6) Aire d'un rectangle = Longueur x largeur =  l * x

On veut  : lx = A

Donc l = A/x = -(x - 8)(x + 3)/x

7) KN = UM = l = -(x - 8)(x + 3)