2.78 Archaeologists measure a pre-Columbian ceremonial structure and obtain the dimensions shown. Determine (a) the magnitude and (b) the direction cosines of the position vector from point A to point B. z 4 m A A FAD A FAC FAB 60 m 40 m 10 m Problem 2.78 2.94 The magnitude of the force FAB is 2 kN. The x and z components of the vector sum of the forces exerted on the tower by the three cables are zero. What are the magnitudes of FAC and FAD? (The tower is 70 -m tall.) D C 40 m 4 m 60 m z B 40 m 10 m Problems 2.93/2.94 8 m 8 m B