Focus of a parabola

Question

If (2,0) is the vertex and y-axis the directrix of a parabola find the focus of the parabola. What does y-axis is directrix mean here?

Answer 1

The parabola is the locus of points that are equidistant from both a given line (the directrix) and a point (the focus).

Normally, you are given the data to give the results in terms of $x$: a directrix $y=\cdots$ for a parabola $y=\cdots$. But in this case, your directrix is $x=0$. Just try to follow the same directives but interchanging $x$ and $y$; you will obtain a parabola of the form $x=\cdots$ instead of $y=\cdots$