A beam is to be hoisted using two chains. Determine the magnitude of forces FA and FB acting on each chain in other to develop a resultant force T directed along the positive y axis.
Given θ1=30 degrees,
θ=45degrees,
T= 800N

Zinindo - it would help to post a sketch so we can understand the problem. But it seems that the two chans are each at some angle from the vertical. The vertical component of force in each chain is Fa x cos(angle a) and Fb x cos(angle b) respectively, and you need the sum of the two to equal the weight of the beam. You also need the horizontal components of Fa and Fb to cancel out. Can you take it from here?