Static equilibrium 3D, traffic light problem

[J-dizzal]

Homework Statement

The vertical and horizontal poles at the traffic-light assembly are erected first. Determine the additional force and moment reactions at the base O caused by the addition of the three 100-lb traffic signals B, C, and D. Report your answers as a force magnitude and a moment magnitude.

Homework Equations

Sum of all forces and moments =0

The Attempt at a Solution

I got the Force at O right, but the moments I am not sure how to sum them

[/B]Edit: solved by finding magnitude of M

 

[Dr. Courtney]

You have two components of the moment vector. Compute the magnitude of the vector.