Explicație pas cu pas:
a + b + c = 180°
{ a , b , c } d.p. { 2 , 7 , 9 }
a/2 = b/7 = c/9 = k
a = 2k
b = 7k
c = 9k
2k + 7k + 9k = 180°
18k = 180°
k = 180° : 18
k = 10°
a = 2 × 10°
a = 20°
b = 7 × 10°
b = 70°
c = 9 × 10°
c = 90°
a+b+c=180°
{a, b, c} d.p. {2, 7, 9}
a÷2=b÷7=c÷9=k=>a=2k=>b=7k=>c=9k
2k+7k+9k=180°
9k+9k=180°
18k=180°
k=180°÷18
k=10°
a=2×10°
a=20°
b=7×10°
b=70°
c=9×10°
c=90°
________________________________________
Verificare: 20°+70°+90°=90°+90°=180°
