00:02
Okay, the best way to do it, let's see if curl is zero or not.
00:05
Okay, so what's curl? i, j, k, d, dx, d, dy, d, dz.
00:17
You know, there are those formulas.
00:20
If you can memorize it or your professor lets you use a formula sheet, maybe you can use that.
00:28
But when you don't know any formula, i mean, you don't want to memorize anything, this is what i do.
00:35
Just check the curl.
00:39
So curl of f is, what is it? let's see.
00:43
I component is derivative of cosine of z minus cosine of z.
00:54
And then j component is zero minus zero.
01:01
And k component zero minus zero and zero.
01:05
So guess what? curl is zero.
01:07
Okay, so it's conservative.
01:13
Conservative.
01:14
So we need to find little f, which is gradient of f is equal to f.
01:21
So let's start with df dx.
01:24
Df dx should be equal to the i component of the big f, which is one...