PROBLEM STATEMENT 

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Follow the four-step plan:

1. Equilibrium: FBD and equilibrium equation for joint D. Assume all members in tension in your FBD. You should recognize that the problem is INDETERMINATE.
2. Force/elongation equations:  Write down the e = FL/EA equation for each of the three truss members.
3. Compatibility equations: Recall that for a truss element, the displacement components of joint D is related to the elongation of the jth truss element elongations through: e_j = u_D cosθ_j + v_D sinθ_j. Recall that the element angles must be measured: 1) at the base of the element, 2) from the x-axis, and 3) in the CCW direction. You will have three compatibility equations.
4. Solve: At this point, you should have a sufficient number of equations to solve for the load in the three truss elements.

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