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Problem: Determine the magnitude of the moment of each of the three forces about the axis AB. Solve the problem (a) using a Cartesian vector approach and (b) using a scalar approach

Variable Solution:

Givens: 
F1 = 60 [N]
F2 = 85 [N]
F3 = 45 [N] 
a = 1.5 [m]
b = 2 [m]

Numerical Solution:
M_AB(F1) (scalar) = b⋅F1⋅sin(tan^-1(a/b))
→(2 [m])(60 [N])⋅sin(tan^-1((1.5 [m])/(2 [m])))
M_AB(F1) = 72 [N⋅m] 

M_AB(F1) (vector) = ab⋅f1⋅(a²+b²)^-1/2
→(1.5 [m])(2 [m])(60 [N])⋅((1.5 [m])²+(2 [m])²)^-1/2
M_AB(F1) = 72 [N⋅m] 

M_AB(F2) (scalar) = 0
M_AB(F2) (vector) = 0

M_AB(F3) (scalar) = 0
M_AB(F3) (vector) = 0