In the pinned truss shown in Figure, pin 3 is fixed. The pin at 1 is free to move in a vertical guide, and the pin at 2 can only move along the horizontal guide. If a force P is applied at pin 2 as shown, determine U2 and V1 in terms of P. Calculate all
reaction forces at pins 1, 2, and 3, and check to see whether equilibrium is satisfied. Formulate the stiffness matrix with factor EA/l by the finite element method.