Find the coordinates of the focus, axis of the parabola, the equation of the directrix and the length of the latus rectum.`x^2=-9y`

Options

A. `y=-9/4,8`
B. `y=9/4,9`
C. `y=-9/4,9`
D. None of these

Answer

B

Explanation

Given equation of parabolais `x^(2)=9y,` which is of the from `x^(2)=-4y,`
i.e .focus lies on the negative direction of Y-axis.`
here, `4a=9 `
` rArr a=9/4`
`therefore equation of directrix is y=a `
`therefore y=9/4 ` and length of latusretum =4a =4x 9/4 =9