Hi,
How would I do this question? https://m.imgur.com/a/DwFiK
Wasn't very sure but I'm getting 4/3 which isn't correct. My working is shown in the image.
Thanks
You need to set up equations for the forces with respect to the object on which the forces are acting i.e. they must be with respect to the block. In other words, your angle should be next to the block.
The right-hand angle of the triangle can be given by
This angle is the same as the angle which you have drawn in (in pencil) just to the right of the block.
Similarly, we can find the angle of the left-hand corner of the triangle
I will now work with only the forces acting
parallel to the horizontal bar (i.e. directly left and right), assuming the system is in equilibrium.
So then we have
as required
Note you can also work with the force perpendicular to the horizontal bar (i.e. up and down), and you should get the same answer.
Hope this helps