[tex]Notam\ unghiurile\ a,b,c:\\
\{a+b,b+c,a+c\}dp\{3,4,5\}\Rightarrow\frac{a+b}{3}=\frac{b+c}{4}=\frac{a+c}{5}=k\Rightarrow a+b=3k,\\ b+c=4k,a+c=5k\\
a+b+c=180\\
2a+2b+2c=360\\
(a+b)+(a+c)+(b+c)=360\\
3k+5k+4k=360\\
12k=360\Rightarrow k=30\\
a+b=90\\
b+c=120\\
a+c=150\\
.......................+\\
2(a+b+c)=360\\
(a+b)+c=180\\
90+c=180\Rightarrow c=90\ grade\\
b+90=120 \Rightarrow b=30\ grade\\
a+30=90\Rightarrow a=60\ grade.[/tex]
