Răspuns:
Explicație pas cu pas:
m∡(A)=2*m(∡B)
m(∡C)=3*m(∡A)
m∡A=2m∡B
m∡C=6m∡B
2m∡B+6m∡B+m∡B=180° (suma masurilor unui triunghi=180°)
9m∡B=180°
m∡B=180°:9
m∡B=20°
m∡A=2*m∡B→m∡A=2*20°→m∡A=40°
m∡C=6*m∡B→m∡C=6*20°→m∡C=120°
deci
m∡A=40°
m∡B=20°
m∡C=120°
40+20+120=180°
