Angle between tangent and foci. (Involve vector calculus)

athrun200

1. The problem statement, all variables and given/known data
See the photo on the left


2. Relevant equations



3. The attempt at a solution

Attached Thumbnails

   

HallsofIvy

You must show some work of your own or this thread will be deleted.

athrun200

In fact, I type my work on the computer, the photo I have shown is already my work.
That is not solution, that is my attempt to solution. So it may be wrong.