A tubular post of outer diameter d2 is guyed by two cables fitted with turnbuckles (see figure). The cables are tightened by rotating the turnbuckles, thus producing tension in the cables and compression in the post. Both cables are tightened to a tensile force of 110 kN. Also, the angle between the cables and the ground is 60°, and the allowable compressive stress in the post is σc = 35 MPa.
If the wall thickness of the post is 15 mm, what is the minimum permissible value of the outer diameter d2?

Cable Turnbuckle Post dh 60 60