Let x^2=4py be equation of parabola. Then equation of directrix is y=-p coordinates of focus are (0,p) and axis of symmetry is y-axis.
In this case the equation of parabola is
x^2=-36y
Therefore,
4p=-36
p=-9
Using the facts stated above we can write equation of directrix and coordinates of focus.
Directrix is line with equation y=9, focus is the point with coordinates (0,-9) and axis of symmetry is y-axis.
https://en.wikipedia.org/wiki/Parabola
No comments:
Post a Comment