00:01
They want us to sketch this curve here.
00:04
And before we actually try to do this in three dimensions, notice that since x is constant, we can try to figure out what's going on in the y, z plane, and then translate that into three dimensions.
00:18
So let's go ahead and draw the yz plane over here.
00:24
Okay, so if, so i'll write this in the corner, we have y is equal to cosine t.
00:32
Z is equal to to sine t.
00:36
So let's just plug in a couple of points.
00:38
So like if t is zero, then cosine is one.
00:44
So y is going to be one of the axis.
00:46
So let me just put that there.
00:48
And then sign of zero is zero.
00:51
So we're going to be zero of the z.
00:52
So we're going to be starting here.
00:54
So t is equal to zero.
00:56
Now another good point to maybe is going to be like pi half.
01:02
So if we plug in pi half into here, so cosine is going to be zero, so we go zero up the y -axis, and then we plug in pi -half to sign, that gives us one.
01:15
So we'd have two times one, so it would be one, two.
01:18
So we'd be right here.
01:19
So this is t is equal to pi -half.
01:23
And you might kind of notice that this is going to give us an oval.
01:27
So the next point we would probably want to pick is, going to be t is equal to pi which is going to give us negative one zero and then after that we can pick t is equal to three pi halves which is going to give us this point down here and then lastly we would wrap back around two pi and we get there so our sketch is going to look like this and i guess that kind of looks like an oval and it's oriented so it goes from t0 to t pi half so it increases in this direction.
02:04
So we have the normal counterclockwise direction that we're rotating this.
02:08
So what we now know is when we translate this into three dimensions, so this is essentially like we looked at this plane from like above the x -axis.
02:21
So like we're above the x -axis right now.
02:24
And this is what we see this circle.
02:26
And since x is constant, it's just going to pretty much look like our oval here.
02:31
So let's go ahead and draw that out.
02:35
So we have some tick marks i'll put down, and then this is x, y, and z.
02:44
So just to get an idea, so x is equal to 1 is right here...