Fie a; b; c; d; e; f, cele 6 arce, fiint proportionale cu numerele 1; 3; 6; 7; 8; 11, putem scrie: [tex] \frac{a}{1} = \frac{b}{3}= \frac{c}{6}= \frac{d}{7}= \frac{e}{8}= \frac{f}{11}= \frac{a+b+c+d+e+f}{1+3+6+7+8+11}= \frac{360}{36}=10 [/tex]
Deci a=10×1=10°; b=3×10=30°; c=6×10=60°; d=70°; e=80°; f=110°
