Question

Show that the points A (1, 2, 3), B (–1, –2, –1), C (2, 3, 2) and
D (4, 7, 6) are the vertices of a parallelogram ABCD, but it is not a rectangle.

Answer 1

@Noemi95

Answer 2

Compare the "slope" of opposite sides. A to B vs D to C, for example.
Use your dot product to determine the angle at any intersection.

Answer 3

Hint: One way is to show that the angles in ABCD are not orthogonal.

Answer 4

^ listen to them!(:

Answer 5

Thanks