there are lots of references for this particular structure, you'll get more from them than posting here (we can be cranky, or just cranks).
consider each piece in isolation as a free body (research that if you don't understand).
consider the structure as a whole as a free body.
together you should get close to a solution.
You've got part of the solution already ... the three members are not the complete structure, it needs something linking the two inclined legs (the actuator) to hold the legs in position (which you can see for yourself with a model or a thought exercise).
another day in paradise, or is paradise one day closer ?