So, this is the truss I have to solve, more precisely I have to find forces in all of the members of the truss. That is why I used method of joints. I started from the joint A and realised without calculating that members attached to it (Fab and Fal) are the zero force members.
PICTURE ON THE RIGHT: The only joint with 2 unknown members that has left after calculating members of joint B is joint L. But here is the problem. Since I can only use 2 equations - sum of the forces in the X and Y direction (in method of joints), I don't know how to find Flk and Flc, since those are not neither vertical nor horizontal forces. I know I should split those into their components (vertical and horizontal), but since they are both unknown members (so are the components), I don't see way to calculate any of them.