I am dealing with a statics problem in the following link. This question is from the courtesy of Engineering mechanics, Statics by R.C. Hibbeler, 13th edition.
Before applying vertical forces F and -F, 60 Ib of force causes 1.5 ft of stretch in springs. With the exercise of the two forces, springs stretch some more and this can be found from the geometry of the problem. This stretch is 0.27 ft at points C and D. Finally, again due to geometry F equals the force in one of the springs.
I sum the initial stretch and the final stretch and multiply this with the stiffness of one spring but do not arrive at the true answer.
What am I doing wrong here?