00:01
All right, so let's go ahead and solve this problem.
00:03
So we're given f, which is a vector 1, comma, x plus y, z, comma, x, y, minus square root of z.
00:11
And we have a path c, which is the intersection or the boundary in the first octant and the plane 3x plus 2y plus z is equal to 1.
00:25
And i've already drawn the in 3d, the blue path is what we're looking at.
00:32
That's the boundary of c.
00:33
So we want to evaluate the integral, the integral of c, f .dr.
00:45
But we're going to use stokes theorem to evaluate this thing.
00:49
So it is going to be the double integral through the surface s, where s is going to be this triangular region, curlf.
01:08
D .s.
01:12
And as usual, instead of just doing d .s, you can do curl f times the normal vector, ds.
01:25
Okay? all right.
01:29
So, let's start with finding the curl.
01:38
This is going to be the vector, x minus y, comma negative y, comma 1.
01:47
It's quite straightforward.
01:48
So i'll let you, take a look at the details by herself.
01:52
And the normal vector, because the plane is given to you, it's quite straightforward to see.
01:59
I'm not going to normalize it, but we know that this is going to be parallel to 3 comma 2, comma, 1.
02:09
Okay? so we know that curlf .n, the dot product will simplify to 3x minus 5y plus 1...