disusun mirip pada gambar.
Diketahui:
F₁ = 30 N
F₂ = 70 N
F₃ = 30 N
ΣFₓ = F₁ₓ + F₂ + F₃ₓ
ΣFₓ = F₁ cos 60° + F₂ + F₃ cos 60°
ΣFₓ = 30 . 1 + 70 + 30 . 1
2 2
ΣFₓ = 100 N
ΣFy = F₁y – F₃y
= F₁ sin 60° – F₃ sin 60°
= 30 . 1 √3 – 30 . 1 √3
2 2
ΣFy = 0
FR = √ΣFₓ² + ΣFy²
Jadi, FR = 100 N