A 108 N lamp is hung up with two ropes that each make 20º angles with the horizontal. What's the tension in the ropes? What's the tension if the angle is 60º?
I answered the problem a while ago. Here is the copy of my answer:
With symmetry, apply Newton's second law in vertical direction:
2Tsinθ = mg
T = 108/(2sinθ)
θ = 20o, T = 158 N
θ = 60o, T = 62.4 N