1. Dec 11, 2011

### pyroknife

1. The problem statement, all variables and given/known data
I have attached the problem. I am confused about how they got x(θ) and h(θ). From the diagram it looks like they made it with reference to the triangular support beam. Why?

2. Relevant equations

3. The attempt at a solution

#### Attached Files:

• ###### Untitled.png
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2. Dec 12, 2011

### Spinnor

This is late and my be of no use. You wrote,

From the diagram it looks like they made it with reference to the triangular support beam. Why?

It is a reference point that doesn't move? h(θ) is pretty straight forward, and if you set θ = 0 , x(0) = 3b/2 makes sense.

3. Dec 12, 2011

### gnulinger

The length of one rod is b. b/2 at angle θ coincides with the vertical position that you want to use to define h(θ). From basic trig, h/(b/2) = sin(θ). Thus h(θ) = b/2*sin(θ).

Similarly x coincides with the horizontal position that the 1 + 1/2 rods make at angle θ. So then x = b*cos(θ) + 1/2*b*cos(θ) = 3b/2*cos(θ).