PARABOLAS

[r267747]

1)I don,t know how to show that the =n y(square) -8y -x +19 = 0 represent a parabola. Find its vertex,focus and directrix.
2)Find the =n of the parabola with vertex at the origin and satisfying the condition:
Focus(0,-3); Directrix y=3
Also find the length of latus rectum.
MY WORK
I have find the =n but I don't know how to find the length of latus-rectum.

 

[galactus]

The length of the latus rectum is 4p. In other words, 4 times the distance from the focus to the vertex.

The latus rectum is the chord that passes through the focus. It is parallel to the directrix.

 

[garf]

Hi r267747!
You would fine useful this site:
http://www.intmath.com/Plane-analytic-g ... /Intro.php

It is fine for get some lessons and will allow you solve your homework. Hint: Your parabola has directrix parallel to X and n determine if it is translated from (0,0).
Hope this helps, let me kow if you have any question.
GARF