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=20y`

Therefore,

`4p=20`

Divide by 4 in order to obtain `p.`

`p=5`

Using the facts stated above we can write equation of directrix...

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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=20y`

Therefore,

`4p=20`

Divide by 4 in order to obtain `p.`

`p=5`

Using the facts stated above we can write equation of directrix and coordinates of focus.

**Directrix is line with equation `y=-5` focus is the point with coordinates `(0,5)` and axis of symmetry is `y`-axis.**

**Further Reading**