Calculating Total Moment of Force F1 about Point A

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To calculate the total moment of force F1 about point A, the formula used is moment = perpendicular distance x force. The user determined the resultant distance as sqrt(20) and attempted to apply trigonometric functions for angles 35 and 55 degrees but encountered difficulties. The correct approach involves identifying the angle θ between the line connecting point A to the force application point and the force's line of action. To find θ, one must drop perpendiculars from point B to both the force line and a line through A parallel to the force. This method will help in accurately calculating the moment.
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Homework Statement


http://i.imgur.com/Laub8lL.png
Find the total moment created by force F1 about point A.

Homework Equations


moment = perpendicular distance x force


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.

Please help me
 
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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
 
How do i find theta though?
 
See drawing
 

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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?
 

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