# Problem 404 Roof Truss - Method of Joints

### In the solution, second line

In the solution, second line under the first sketch (of reaction forces at supports):

the sum of the moments about A = 2xVD=450x+(450sin30∘)(2x)

How is the last term (2x) determined?

### The 450 N at B was resolved

The 450 N at B was resolved into components at D. The vertical downward component is at distance 2x from A.

### I tried solving this part but

I tried solving this part but this time, considering all forces with respect to point A, here's what I got:

VD(2x) = 450(x)+(450sin30)(x)+(450cos30)(xtan30)
VD=450

I think what they've shown is a simplified equation already.