Răspuns :
A/12=B/13=C/11, A+B+C=360°, B=13A/12, C=11A/12, inlocuim B si C in suma
A+13A/12+11A/12=360° numitor comun 12, 12A+13A+11A=4320, 36A=4320
A=4320/36=120°, B=13*120/12=130°, C=11*120/12=110°
A/12=B/13=C/11, A+B+C=360°, B=13A/12, C=11A/12, inlocuim B si C in suma
A+13A/12+11A/12=360° numitor comun 12, 12A+13A+11A=4320, 36A=4320
A=4320/36=120°, B=13*120/12=130°, C=11*120/12=110°