This is one of the difficult question in this chapter.

The vectors a = 3i - 4j - k (3, -4, -1) and b = 2i + 3j -6k (2, 3, -6) are the diagonals of a parallelogram. Show that this parallelogram is a rhombus, and determine the lengths of the sides and the angles between the sides.

Yes, I know what a rhombus is and some of it's properties.

I used the dot product for the 2 Vectors given which = 0 therefore I know that the 2 vectors bisect each other in the rhombus. So, how do I find the side lengths and the angle? Thanks