Saturday, 10 May 2014

`x^2=-36y` Graph the equation. Identify the focus, directrix, and axis of symmetry of the parabola.

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.                         

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.                         

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