\begin{align} &\cssId{Step1}{ΣF_{horitzontal} = 0}\\[3px] &\cssId{Step2}{F_{AB}·cosφ - F_{CD}·cosφ = 0}\\[3px] &\cssId{Step3}{ΣF_{vertical} = 0}\\[3px] &\cssId{Step4}{-F_{AB}·sinφ + F_{CD}·sinφ = 0}\\[3px] &\cssId{Step5}{F_{AB} = F_{CD}}\\[3px] &\cssId{Step6}{F = mg}\\[3px] &\cssId{Step7}{F = 4·9,81 = 39,24N}\\[3px] \end{align}

1. Igualem la suma de les forces horitzontals a 0.
2. Desenvolupem \(F_{AB}\) horitzontal i \(F_{CD}\) horitzontal.
3. Igualem la suma de les forces verticals a 0.
4. Desenvolupem \(F_{AB}\) vertical i \(F_{CD}\) vertical.
5. Igualem \(F_{AB}\) i \(F_{CD}\).
6. Desenvolupem F.
7. Sustituïm les dades pels seus valors.