AB=2r (r is radius of small cylinder)
AB=OA=OB (since triangle is equilateral)
therefore, OB=2r
B is center of cylinder, therefore, B to
closest side of barrel (lets call it point X)=r
Since OB=AB, OX=radius of barrel=3r (OB+BX)=(given in qn but cant
see clearly, call it R)
So, OB=2r=R/3 *2