I would like to clarify if the equations that I got from this figure are correct.

enter image description here

$$-T_{CD}sin(30) + T_{DE}cos(0) = F_x = 0$$

$$T_{CD}cos(30) - \frac{W}{2} = F_y = 0$$


$$-T_{ED}cos(0) + T_{EG}sin(10) = F_x = 0$$

$$T_{EG}cos(10) - \frac{W}{2} = F_y = 0$$


1 Answer 1



  • the points D and E are pivot joints, or equivalently if all the connecting elements are wires/cables,
  • GE does not change in length

then you've written the right type of equations.

Some minor notes:

  • The equilibrium is $\sum F_x $ not $F_x$ (and $\sum F_y $) so for example:

$-T_{CD}sin(30) + T_{DE}cos(0) = F_x = 0$

is properly written:

$$-T_{CD}sin(30) + T_{DE}cos(0) = \mathbf{\sum F_x} = 0$$

  • Usually the symbol $T$ in this context is used to denote the tension on a wire in that case, regarding the tension of the cables in GE, I would have preferred to write:

$$-T_{ED}cos(0) + \mathbf{\color{red}2\cdot}T_{EG}sin(10) = \sum F_x = 0$$

$$\mathbf{\color{red}2\cdot}T_{EG}cos(10) - \frac{W}{2} = \sum F_y = 0$$

The reason for $\mathbf{\color{red}2}$ is that you have two cables between GE and therefore the tension on each cable will be $T_{EG}$.


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