1. ## Paralellogram Unnsovlable Zeroes!

Here is the question in hand:

The problem is, I try using the cross product and I get zero.

Let the first point be A, second be B, third be C and fourth be D;

So how do I solve this?

0 is not an accepted answer.

2. Originally Posted by JoeyCC
Here is the question in hand:

The problem is, I try using the cross product and I get zero.

Let the first point be A, second be B, third be C and fourth be D;

Let $u = \vec{CD}$ and $v = \vec{AC}$ with the third compenent of each to be zero, then cross them and take the magnitude.