(Solved): 4-87. Two couples act on the frame. If \( d=6 \mathrm{ft} \), determine the resultant couple momen ...

4-87. Two couples act on the frame. If \( d=6 \mathrm{ft} \), determine the resultant couple moment by (a) summing the moments of the two couples and (b) resolving each force into \( x \) and \( y \) components and then summing the moments about \( B \) of all the force components.