00:01
Sketch the vector field.
00:02
This kind of vector field might be easier to look at if you think of it in terms of polar coordinate.
00:10
So if you do the change of coordinate, it might make it a lot easier to draw the vector field.
00:19
Because the denominator will be r and numerator will be r -sign theta i plus r cosine theta j, and therefore it will be sine theta.
00:32
I plus cosine theta j and we know that the vector has a constant length everywhere and the direction of the vector just depends on theta by the way given a point this will be the vector cosine theta sine theta and sine theta cosine theta will just be the reflection of this factor with respect to the x equals y line so what i mean is that let's draw a circle.
01:25
Probably should open another page.
01:29
So we have f of theta, r theta equals sine theta i plus cosine theta j.
01:53
Let's draw a circle.
02:04
And let's say consider this point.
02:09
This point theta is pi over two, so sine theta is to one.
02:13
And the cosine theta is zero.
02:16
So we have a one.
02:17
And notice this one is perpendicular to the normal direction of a circle which is given by cosine theta, sine theta.
02:34
So for example at this point, sita is zero, so sine theta is zero, cosine theta is one.
02:44
So this will be the wide direction...