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## Homework Statement

In the figure , the moment of a certain force F is 180ft - lb clockwise about O and 90ft-lb counterclockwise about B. If its moment about A is zero, determine the force.

## Homework Equations

Moment of a force

Mo = Fy(x)

Mo = Fx(y)

## The Attempt at a Solution

Since its moment about A is zero then the force passes through A down to the right because the problem mentioned its directions:

Moment of F w/ respect to O = 180ft - lb = Fx(y)

180ft - lb = Fx (3)

Fx = 30lb

Moment of F w/ respect to B = 90ft - lb = Fy(x)

90ft - lb = Fy(6)

Fy = 15lb

using Summation of components:

F^2 = (30)^2 + (15)^2

F = 61.8lb

the answer at the book is 75lb down to the right at theta = 36.9 degrees

is the book a typo?