1. The problem statement, all variables and given/known data A structure is made of 3 members, AD, AC, and BD (as shown in the attached image). A and B are NOT directly connected. There is also a pulley attached to D with radius 0.15 m. 1 end of the cable is attached to a 500 N weight, the other on is fixed in a horizontal sense. A is on a frictionless pin support. C is on a roller support; its line of action is directed along the y-axis. There is also a 300 N force directed downwards in the center of AD. Determine the forces on member AD. 2. Relevant equations Sum of forces in the X = 0 Sum of forces in the Y = 0 Sum of moments about a point = 0 3. The attempt at a solution I took the reaction on the center of D, which is +500 N in both the X and Y, then applied this force on member BD, reversing its sense. B is the only other point, therefore the forces on point B will be equal to the forces on D, reversed in sense. Then I moved to member AC. At B there is 500 N down, 500 N left. I took the moment about A: -500(.5) + Cy(1.0), Cy = +250 N, therefore Ay = -250 N, and Ax = +500 N. At this point I got stuck because I just don't understand why the book gives the answer as "On AD: Ax = -300 N, Ay = 0 N, Dx = +300 N, and Dy = +300 N". So it became pretty clear I did something wrong. I've been moving the numbers around in my head but I don't get how the book got 300 N as a magnitude for any force of Dx or Dy. There's probably something simple I'm missing. Any help is appreciated.