00:01
Right, vector c and vector d in terms of vectors a and b.
00:06
Note that this point m here is the midpoint of the line segment joining q and r.
00:17
Okay, so first, if this was a and this was b, and i formed a parallelogram, then qr is this, and then this is the other diagram.
00:36
And what's true is that diagonals of a parallelogram meet at the point, at the midpoint of each, or they bisect each other.
00:50
So this is the point that's halfway between.
00:54
So then when you look at vector c, you can see it's half of a plus b.
01:01
So vector c equals half of vectors a plus b.
01:15
All right, now let's look at vector d, which is right here.
01:20
So i'm going to erase this picture...