Showing posts with label attributes of parabola. Show all posts
Showing posts with label attributes of parabola. Show all posts

Monday, June 1, 2009

Determine the Attributes of parabola

An Equation of Parabola helps us to find attributes of parabola, after simplification of any given equation we can calculate vertex, focus, directrix etc of the parabola. Here is one such example.

Topic : Parabola

Parabola is a Geometrical figure with standard form x ² = -4ay

Question : Find the vertex, focus, diretrix, and axis of symmetry of the parabola y2+3x-2y-11=0
Solution :

y2+3x-2y-11=0

subtract 3x and add 11 on both the sides

y2+3x-2y-11=0

- 30 + 11 = - 30 + 11
-----------------------------
y2-2y = - 3x + 11

by completing the square method

y2-2y + 1 = - 3x + 11 + 1

(y - 1)2 = - 3x + 12

(y - 1)2 = - 3(x - 4)

Now x - 4 = 0 so x = 4

and y - 1 = 0 so y = 1

So vertex is (4,1)

Standard form is given by

(y - k)2 = 4p(x - h)

so here 4p = -3

p = - 3/4

Focus = (4 + (-3/4), 1) = (4 - 3/4 , 1) = (13/4, 1)

Directix x = 4 - (-3/4)

x = 4 + 3/4

x = 19/4

Axis of symmetry is

x = 4


Solving number of problems like this will help you to solve even difficult problems quickly, for more assistance contact calculus help or geometry help.