Bonjour,
1) Calculer BC.
BC = (AB - 1/3) cm
BC = (17/10-1/3) cm
BC = (17/30) cm
BC = 41/30 cm
2) Calculer CA.
CA = (BC - 11/20) cm
CA = (41/30 - 11/20) cm
CA = (49/60) cm
CA = 49/60 cm
3) Calculer le périmètre de ce triangle :
P = AB + BC + CA
P = 17/10 + 41/30 + 49/60
P = 233/60 cm
Bonne journée :)
