The helicopter view in Fig. P3.29 (page 74) shows two people pulling on a stubborn mule. The person on the right pulls with a force F S 1 of magnitude 120 N and direction of u1 5 60.0°. The person on the left pulls with a force F S 2 of magnitude 80.0 N and direction of u2 5 75.0°. Find (a) the single force that is equivalent to the two forces shown and (b) the force that a third person would have to exert on the mule to make the resultant force equal to zero. The forces are measured in units of newtons (symbolized N).