Assertion: parabola's directrix | /r/AtLocation | x = p
Facets:
Source sentences:
text: Directrix is at x = p, as it is equidistant from the vertex as vertex is from focus .this shows that if p < 0, then the parabola opens towards left.
text: Directrix is at x = p, as it is equidistant from the vertex as vertex is from focus .this shows that if p < 0, then the parabola opens downwards.