Ok je te montre ne details ce que j´ai fait
Soit x=ia
x=0.7(x+5)
x=0.7x+3.5
x-0.7x=3.5
0.3x=3.5
x=35/3
ia=35/3
Apres propriete de phytagore
IA²=PI²+7²
(35/3)²=PI²+49
1225/9=PI²+49
(1225/9)-49=PI²
784/9=pi²
V(784/9)=28/3=PI
Perimetre= PI+IA+PA
perimetre= (28/3)+(35+3)+7
= 63/3 +7
= 21+7=28