In the following sketch , you can see the North light truss.
The dimensions have already been given .
The span is 7.5 M and the rise of the truss is 1.5m. The vertical members are known as Struts ( These carry compression force ) and the diagonal members are known as Ties ( These carry tensile force ).
The rafter on the top is made of two equal angles ( back to back ) of 65 x 65 x 6 @ 5.8 Kg/M and the Bottom rafters have been made with two equal angles ( back to back ) of 50 x 50 x 6 @ 4.5 Kg/M.
All the ties have been fabricated with ISA 50x50x6 @4.5 Kg/M and
the Struts have been made with ISA 65x65x6 @ 5.8 kg /M.
A node point is a junction where two or more members are connected.
usually , there shall be a Gusset plate provided at this junction.
Second step is to find out the lengths of individual members.
The final solution works out as follows :