Bonjour
a=3 = 45/15 ; b = 8/3 = 40/15 ; c = 13/15
a)
périmètre = a+b+c = 45/15 + 40/15 + 13/15 = 98/15
1/2 périmètre = p = (98/15)/2 = 98/30 = 49/15
b)
p - a = 49/15-45/15 = 4/15
p - b = 49/15-40/15 = 9/15
p - c = 49/15 - 13/15 = 36/15
Aire = V(49/15 ( 4/15)(9/15)(36/15) ) = V (63504/50625) = V 1.2544 = 1.12