4. A single force f is applied at a point " O " but it was replaced with a couple M and a force F. Find the original single force f applied at point O : Namely, determine the direction and magnitude of this force f, and find the distance " a ". Note that F=300N,M=1000Nm, and " a " is measured along the arm of the wrench which is oriented at an angle of =30 to the horizontal as shown