In order to achieve stability, the sum of secondary forces and secondary couples must be ——- and their respective polygons must be ………
A. Zero, Closed
B. one, Open
C. Zero, open
D. one, closed
Answer:A
In order to achieve stability, the sum of secondary forces and secondary couples must be ——- and their respective polygons must be ………
A. Zero, Closed B. one, Open C. Zero, open D. one, closed