Bonjour,
a.
P = 3x + 2 + 2x + 1 + x + 3
b.
3x + 2 + 2x + 1 + x + 3 = 18
6x = 18 - 2 - 1 - 3
6x = 12
6x / 6 = 12 / 6
x = 2
c. AB = 3 × 2 + 2 = 8
BC = 2 × 2 + 1 = 5
AC = 2 + 3 = 5
C'est donc un triangle isocèle.
