00:01
Okay, we are going to be finding the principal unit normal vector, and we're going to do that by first finding our tangent vector.
00:09
So to do that, we'll take the derivative of r of t, and then we're going to be dividing by the magnitude of our prime of t.
00:17
So for our derivative, the derivative of ln of t is 1 over t, and that will be in the i direction, and then we just have 1 in the j direction.
00:27
We place a two in there.
00:29
We'll get one half in the i direction and one in the j direction.
00:35
So for our magnitude, we will square each of those add them together and take the square root.
00:42
Well, one -fourth plus one is like five -fourths.
00:45
So we can do a square root of five over two.
00:50
So to write that tangent vector, the unit tangent vector out, i will be distributing a two over square root of five.
01:00
When i distribute that into i, the twos cancel out.
01:03
I just have a one over square root of five in the i, but then i have a two over square root of five in the j.
01:10
So where does that place me? that place me in quadrant one...