Răspuns:
a+b+c= 110×3
a+b+c=330
[tex]a = \frac{b + c}{2} = > [/tex]
=> 2a=b+c
b=c+40°
=> 2a= c+ c+40°
2a=2c+40° | :2
a= c+ 20°
a+b+c =330°
c+20+c+40+c=330°
3c+60=330°
3c=270°
c=90
b=90+40
b=130
a=110
