fie <A= a
<B=b
<C=c
a/2=b/3=c/4=p=> a=2p,b=3p, c=4p
stim ca a+b+c=180°
=> 2p+3p+4p=180
9p=180=> p=20
=> a=2×20=40
b=3×20=60
c=4×20=80
