Answer:
a) 
b) 
c) the points of the form (x, -x) for x≠0
Step-by-step explanation:
a)
If φ(x, y) = arctan (y/x), the vector field F = ∇φ would be
On one hand we have,
On the other hand,
So
b)
The domain of definition of F is
i.e., all the plane X-Y except the (0,0)
c)
Here we want to find all the points such that
where k is a real number other than 0.
But this means
So, all the points in the line y = -x except (0,0) are parallel to the vector field F, that is, the points (x, -x) with x≠ 0
u is at (1,-2)
V is at (-6,-6)
using distance formula it is about 8.06 long
so Answer is C
Hello there,
I hope you and your family are staying safe and healthy during this winter season.

We need to use the Quadratic Formula*
, 
Thus, given the problem:

So now we just need to plug them in the Quadratic Formula*
, 
As you can see, it is a mess right now. Therefore, we need to simplify it
, 
Now that's get us to the final solution:
, 
It is my pleasure to help students like you! If you have additional questions, please let me know.
Take care!
~Garebear
A point has D) zero dimensions