- #1

Dirac

- 19

- 0

vertex (-2, 3), focus (0,3)

Find the equation of the parabola.

Dirac.

Find the equation of the parabola.

Dirac.

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- Thread starter Dirac
- Start date

- #1

Dirac

- 19

- 0

vertex (-2, 3), focus (0,3)

Find the equation of the parabola.

Dirac.

Find the equation of the parabola.

Dirac.

- #2

lurflurf

Homework Helper

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What have you tried so far?Dirac said:vertex (-2, 3), focus (0,3)

Find the equation of the parabola.

Dirac.

Find the directix. then recall

A parabola is the set of point equidistant from the focus and directix.

Last edited:

- #3

Dirac

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- 0

lurflurf said:What have you tried so far?

Find the directix. then recall

A parabola is the set of point equidistant from the focus and directix.

So far I have got to this

((y-3)^2)=4a(x+2)

What now

Dirac.

- #4

lurflurf

Homework Helper

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a will be the distance between the focus and vertex.Dirac said:So far I have got to this

((y-3)^2)=4a(x+2)

What now

Dirac.

Why is this?

- #5

Dirac

- 19

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lurflurf said:a will be the distance between the focus and vertex.

Why is this?

How does one find the vertex

- #6

lurflurf

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you started out withDirac said:How does one find the vertex

vertex (-2, 3), focus (0,3)

The points of a parabola are equidistant from it directrix and focus.

The vertex is the point closest to them. that is

distance(vertex,focus)<=distance(point on parabola,focus)

with equality only when the point is the vertex.

- #7

Dirac

- 19

- 0

lurflurf said:you started out with

vertex (-2, 3), focus (0,3)

The points of a parabola are equidistant from it directrix and focus.

The vertex is the point closest to them. that is

distance(vertex,focus)<=distance(point on parabola,focus)

with equality only when the point is the vertex.

Could you just post the answer, or would it get up your backside to post something useful in your life

Dirac.

- #8

lurflurf

Homework Helper

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I already said you a is the distance betweenDirac said:Could you just post the answer, or would it get up your backside to post something useful in your life

Dirac.

vertex (-2, 3), focus (0,3)

here you go

a=sqrt[(0-(-2))^2+(3-3)]

=sqrt[2^2]

a=2

Do you understand why?

Can you find the equation of a parabola with

vertex (0,0), focus (0,-4)

- #9

HallsofIvy

Science Advisor

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Dirac said:Could you just post the answer, or would it get up your backside to post something useful in your life

Dirac.

How pathetic. Why in the world would anyone

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