What is the equation of directrix of parabola (4x-3)^2 = -64(2y+1) ?
回答 (2)
2017-02-14 4:25 am
✔ 最佳答案
(4x-3)^2 = -64(2y+1) --->16(x-(3/4))^2 = -128(y+(1/2)) --->(x-(3/4))^2 = -8(y+(1/2)) ---> the equation of directrix y = (-1/2)+2=3/2 
2017-02-14 4:26 am
Your equation can be rewritten as
.. (x -3/4)^2 = -8(y +1/2)
This is the equation of a parabola with vertex (3/4, -1/2) and vertex-to-focus distance (p) such that
.. -8 = 4p
.. p = -2
The directrix will have equation
.. y = -1/2 -p = -1/2 -(-2)
.. y = 3/2
.. (x -3/4)^2 = -8(y +1/2)
This is the equation of a parabola with vertex (3/4, -1/2) and vertex-to-focus distance (p) such that
.. -8 = 4p
.. p = -2
The directrix will have equation
.. y = -1/2 -p = -1/2 -(-2)
.. y = 3/2
收錄日期: 2021-04-24 00:13:35
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20170213190507AAEbYnf