Axially Loaded Members Question

[mneox]

Homework Statement

So I'm trying to do this problem right now. For the most part, I feel like I have 80% of the work done (in terms of finding certain unknowns etc) but I have no idea how to incorporate the θ=3°. What I mean is, what kind of equation can I set up that includes the angle in it? Apparently you don't need trig or anything, so I am a bit lost.

Homework Equations

ƩMb = 0; F_A(a) + F_D(b) - P(c) = 0
F = kΔ
Δ_D/b = Δ_A/a (I used similar triangles to achieve this for when the bar will be pulled down)

The Attempt at a Solution

At the moment, I have found all the unknowns such as the reaction and spring forces etc. I think I am on the right track, but I just have no idea how I can set up an equation using the maximum angle.

Thank you for your help!

 

[nvn]

Hint 1: sin(3 deg) = delta_A/a; but delta_A = F_A/k1.