3a=2b=6c <=> a/91/3)+b/(1/2)+c/(1/6)=(a+b+c)/ (1/3+1/2+1/6)=
=180°/(2/6+3/6+1/6)=180°/(6/6)=180° (am folosit proprietatea de la sir de rapoarte egale, iar a+b+c=180° ca unghiuri de o parte a unei drepte)
Daca 3a=180° => a=60°; daca 2b=180° => b=90° => DB⊥BE.