00:01
Okay, we want to find out that if we hook these together in some way, will we get a parallelogram or not? there might be a fast or a more efficient way, but here is a fast way.
00:11
I'm going to make the vectors between these points, and what i'm looking for is two pair of parallel vectors.
00:23
All right, so first i'm going to calculate a b, and it is one, two, two, and then a c, and it is minus 2, 6, 2.
00:38
And then ad, and it is minus 3, 4, 4.
00:47
And then bc, bc is 3, 4.
00:54
Oh, i better check and see if i did that right.
00:58
So, yeah, minus 3, 4, 4.
01:01
Okay, here's a pair of parallel ones.
01:05
Where my bc, bd, b, d is minus 1, minus 3, so minus 4, 2, 6, and then cd is minus 1, minus 2, 2.
01:26
Oh, that would be 2, 2, okay.
01:39
C to d, minus 1, minus 0, 3 minus 5, 8, minus six.
01:46
It to be three minus two is one.
01:50
One minus negative one is two.
01:53
Oh, there it is.
01:57
All right.
01:59
I know it must be these two because they have the same numbers in them.
02:03
Okay, notice i have one of them is positive one, positive two, negative two.
02:08
And the other is negative one, negative two.
02:11
That's okay.
02:11
If i would have done dc, i would have got the same thing.
02:15
Okay.
02:15
So yes, it is a parallelogram.
02:19
Because we found two pair of parallel sides.
02:25
Okay, and let's see, a is hooked to b and c to d, and let's see a, a to d, b to c.
02:46
All right, so like that...