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musicmar
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Homework Statement
This is actually for an engineering class, but it's pretty basic vector addition.
Determine the angle θ between the two cables attached to the post.
I've attached the picture.
Homework Equations
The Attempt at a Solution
From the picture:
F1:
α=?
β=?
γ= 35°
F2:
α= 45°
β= 60°
γ= 120°
First, to find F2, I used the angles and the formula cos(α)=(F2x/F2)
F2=<282.84,200,-200>
To find F1, I used the 35° from the vertical to find the z component, then used the 20° in the xy plane to find the x and y components.
F1=<215.59,-78.47,327.66>
F1·F2=F1F2cosθ
θ=cos-1(F1·F2/4002)
=cos-1(-600.84/4002)=90.2°
According to the back of the book, the answer is 97.3°. So, I've made a mistake somewhere. Any help finding it would be greatly appreciated.