
### Instruction: help me answer this question Are A(–1, 2, 1), B(1, –2, 5), C(4, –7, 8), and D(2, –3, 4) vertices of a parallelogram?, think step by step
### Assistant: Although AB = CD, BC ≠ AD, so A, B, C, and D are not the vertices of a parallelogram. , The answer is No
