Rotate parabola

[Greg]

What do you do to an equation of a parabola to rotate it?

-> For instance y=root x is y=x^2 rotated 90 degrees clockwise.

Ex. How would I get the equation for a normal parabola with (0,0) vertex,
but opening in a diagonal direction such as towards (+3,+3)?

I realize this would no longer be called a function, because some values
would invariably overlap in ANY rotated parabola except those that open
Straight down and Straight up.

Thanks a lot!
Greg
too...@hurontel.on.ca

[Greg]

Jeroen Neve <jeroen.s...@jwneve.demon.nl> wrote in message
news:941835387.9594....@news.demon.nl...
> You seem to have swapped the values for x and y in the equation.
> Please note that this is not rotating in O, but mirroring in the line y=x.
>
> original function: y = x^2
> mirroring in x=y: x=y^2
> y=+sqr(x) "united with" y=-sqr(x)
>
>
> Jeroen Neve

It is both mirroring x and y, AND rotating 90 degrees but I was looking for
the latter.

By the way, can't you simply use the notation y = +-(root x)? Where the plus
is right above the minus.
(Instead of uniting the negative and positive functions separately.)

Oh well
Greg
too...@hurontel.on.ca

[Virgil]

In article <UjqU3.4155$cz3.1...@nnrp1.uunet.ca>, "Greg"
<too...@hurontel.on.ca> wrote:

One way to do a rotation is to replace each x by x*cos(a) + y*sin(a)
and simultaneously replace each y by -x*sin(a) + y*cos(a).

The resulting graph will be rotated counterclockwise through an
angle a from the original graph. The resulting equation will not
usually be the equation of a function.

--
Virgil
vm...@frii.com

[Jeroen Neve]

You seem to have swapped the values for x and y in the equation.
Please note that this is not rotating in O, but mirroring in the line y=x.

original function: y = x^2
mirroring in x=y: x=y^2
y=+sqr(x) "united with" y=-sqr(x)

Jeroen Neve

Greg wrote in message ...