18.1.3
The constraint equations for material points A, B and C, D, connected by rods 1 and 2, respectively, to a constant l = const and variable length l (t), have the form: (xB - x A) 2 + (yB - yA) 2 + ( ZB - zA) 2 - l2 = 0; (XD-xC) 2 + (yD-yC) 2 + (zD-zC) 2 - [l (t)] 2 = 0. Indicate the number of the rod that places the holonomic stationary connection on the points. (Answer 1)