Question

Consider the parabola with focus (-p, 0) and directrix x = p. (Assume p> 0.)
a. Toward which direction does the parabola open?
b. How does the parabola change as p increases?

Answer 1

The parabola opens down because it cannot cross it's directrix and the focus is inside the parabola.

Answer 2

i thought it opened to the right..

Answer 3

I see now. The directrix is vertical but the focus is (-p,0) so it opens to the left.