00:01
This question gives us a specific vector field and a specific curve and asks us to find a few things from this.
00:06
We need to know what points, if any, where our vector field is tangent to the curve, what points it's normal to the curve, and then we're going to want to sketch our curve and then list some of the vectors f on the curve.
00:22
So our vector f is y over 2, comma, negative x over 2.
00:27
Our curve c is shown by the curve created from y minus x squared is equal to one.
00:33
Before we do anything, we need to parameterize this curve.
00:36
Well, by adding x squared to both sides, we have y is equal to x squared plus one.
00:41
Because we have an explicit formula for y, we can just do this.
00:45
We can make it xt and then y would be t squared plus one, which satisfies that equation that we have there.
00:53
It makes sense.
00:54
So now we can get on with our parts.
00:57
Was to find the points where f is tangent to c.
01:00
So this means points where f and our tangent curve are the same.
01:06
How do we find a tangent curve? we take the derivative of both components with respect to t.
01:11
So we have 1 comma 2t, just taking the derivative there.
01:15
And so now what we need to do is we need to see any points for which y over 2 comma x over 2.
01:24
Dot 1 comma 2t is equal to 1 since this would mean they're parallel so that it would impact to be the same vector so doing the stop product we have y over 2 times 1 plus negative x over 2 times 2 t is equal to 1 so we have a problem we have a mixture of x's and y's and t's well this can be solved by using the formula we have here so x is t y is t squared plus one since we're only looking at the points that are on c this would make sense so we have t squared plus one over two times one plus negative t over two times two t is equal to one further we get t squared plus one over two plus negative two t squared over two equals one so combining these, we would get t squared plus 1 minus 2 t squared over 2 is equal to 1.
02:34
Or we can go ahead and multiply both sides by 2 and combine these terms.
02:39
We have 1 minus t squared is equal to 2 or 1 is equal to 2 plus t squared.
02:48
And that would be t squared is equal to negative 1.
02:52
That doesn't have any real solutions...