Jawabanmu

2014-06-23T14:22:35+07:00
Σζ = ΣF.r
     = F₁r₁ + F₂r₂ - F₃r₃
     = (10)b + (9)b - (12)cos 30° . a
     = (10)(0.25) + (9)(0.25) - (12)(1/2 √3)(0.1)
     = 2.5 + 2.25 - 0.6√3
Σζ = 2.75 - 0.6√3 ≈ 0.426 Nm