Răspuns:
B/C=1/2=>2x<B=<C
<A+<B+<C=180°
90°+<B+2x<B=180°
3x<B=180°-90°
3x<B=90°
<B=90°:3
<B=30°
2x<B=<C
2x30°=<C
<C=60°