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Statics

Two equal uniform rods AB BC are smoothly jointed in B and they're in equilibrium. The end of C lies on a rough horizontal plane and the end of A is freely pivoted at a point above the plane. If alpha and beta are the angles of CB and BA with the horizontal, prove that

mu > 2/[tan(beta)+3tan(alpha)]

Any suggestions? I'm not sure what forces should I consider. I mean, I've tried:
- considering the weights of the rods, their tensions, the friction and the reaction of the ground. Didn't work.
- considering tensions, friction and reaction. Didn't work either.
- considering friction, reaction of the ground, weights and reactions at B (splitting the system in the subsystems AB and BC). Guess? Didn't work.
I don't know what else could be that I'm missing. But there must be something.
(Of course I did the balances of forces, took moments, etc..)

An explanation/suggestion of how it can be solved is very welcomed! :biggrin: