Răspuns:
∡A+∡B+∡C=180° ⇒ ∡B+∡C=180°-78° ⇒ ∡B+∡C=102°
∡B/0,(6)=∡C/0,75=k ∡B/(6/9)=∡C/(75/100)=k ∡B/(2/3)=∡C/(3/4)=k
3∡B/2=4∡C/3=k ⇒ ∡B=2k/3 ∡C=3k/4
2k/3+3k/4=102 /·12 8k+9k=1224 17k=1224 / :17 ⇒ k=72
∡B=2·72/3 ⇒ ∡B=48°
∡C=3·72/4 ⇒ ∡C=54°
78°+48°+54°=180°
Explicație pas cu pas:
