Question 1053790
You should study these, and if still you cannot figure out, tell how it went and more help then.


<a href="https://www.youtube.com/watch?v=M8LGsQMwwj4">deriving equation for parabola if given focus and directrix</a>


<a href="https://www.youtube.com/watch?v=Wworlx39KfQ">Same thing but different oriented and vertex not at Origin</a>