Răspuns :
Unghiurile unui triungi au suma 180 grade
a/3=b/4=c/5=a+b+c/3+4+5=180/12=15
a=15*3
a=45
b=4*15
b=60
c=5*15
c=75
a/3=b/4=c/5=a+b+c/3+4+5=180/12=15
a=15*3
a=45
b=4*15
b=60
c=5*15
c=75
a+b+c=180
a/3=b/4=c/5=k
a=3k
b=4k
c=5k
3k+4k+5k=180
12k=180
k=15
a=3×15=45
b=4×15=60
c=5×15=75