# Finding the value of a moment

1. Feb 20, 2013

### United

1. The problem statement, all variables and given/known data
http://i.imgur.com/Laub8lL.png
Find the total moment created by force F1 about point A.

2. Relevant equations
moment = perpendicular distance x force

3. The attempt at a solution
I got my resultant distance to be squrt(20). With this in mind, I plugged into my calculator:
sqrt(20) x 12 x (insert values listed below)
(numbers in degrees)
cos(35)
sin(35)
cos(55)
sin(55)

and I've had no luck with any of this.

2. Feb 20, 2013

### Basic_Physics

The moment is
FL sin(θ)
where θ is the angle between the line connecting point A and the point where F acts on the structure and the line of action of the force

3. Feb 20, 2013

### United

How do i find theta though?

4. Feb 20, 2013

### Basic_Physics

See drawing

#### Attached Files:

• ###### moment.jpg
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5. Feb 20, 2013

### haruspex

Call the point where the right-angled bend is B.
Drop a perpendicular from B to the line of the force. What's the length of it?
Drop another from B to a line through A parallel to the force. What's the length of that?