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Homework Statement
Determine the angle θ between the 300lb force and the line OC.
I have attached an image of the question
Homework Equations
P°Q = PQcos(θ)
The Attempt at a Solution
I tried finding the vectors AB and OA as well as their magnitudes first
O is the origin
A = (9,0,0)
B = (0, 16, 6)
C =(9, 16, 0)
AB = <09, 160, 60>
AB = <9, 16, 6>
AB = sqrt((9^{2}) + 162 + 6^{2})
AB = 19.31
OA = <90, 00, 00>
OA = <9, 0, 0>
OA = 9
AB°OA = ABOA cos(θ)
<9, 16, 6>°<9, 0, 0> = (19.31)(9)cos(θ)
arccos(81/173.79)
θ = 117.78
It says this answer is not correct and I realize that I haven't included the 300lb force, but how would I take that force into account?
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