00:02
Let x, let x be equal to r cost theta, then y equal to r sine theta.
00:18
So this implies that z is going to be square root of x squared flat y squared divided by three, which is equal to r divided by three.
00:37
So then from here it implies that r is which is from 3.
00:44
The interval of r is from 3 to 4 and that of theta is from 0 to 2 pi.
00:59
So then in the cylindrical coordinates we have r theta to represent it as the x is r cost tita i plus y, which is r sign theta in the j components plus your z, which is r divided by three in the key components.
01:34
So this implies that r far is going to be equal to cost theta.
01:46
So you find the derivative with respect to r.
01:52
So you are getting cost theta i plus sine, sine theta, sign theta, j, plus one over three k.
02:15
That is a derivative.
02:17
Then r, so this at theta means you differentiate with respect to theta.
02:25
And this will give me minus r sign theta i plus r cost theta j and there's no theta component here so that is equal that will be that will go to zero so this implies that so we find a cross product of this our theta so we have in the i we have cost theta so have course teta and this is r minus sign teta and in the j components j i have j this is sign teta and this is r here minus r and this is r course teta so for k components we have one or three then zero...