I know how to change a rectangular equation into a parametric one but can't do it vice versa.

An example is: (x+2)^2/25-(y-5)^2/12=1

I'm flabbergasted!

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- Apr 5th 2009, 10:23 PMcheet0faceParametric equations to rectangular equations.
I know how to change a rectangular equation into a parametric one but can't do it vice versa.

An example is: (x+2)^2/25-(y-5)^2/12=1

I'm flabbergasted! - Apr 5th 2009, 11:27 PMGrandad
Hello cheet0faceThere are no hard and fast rules about doing it this way round, but the equation you mention is a fairly standard one - it's a hyperbola, and a variation on the simpler version:

except that its centre has been moved from the origin to .

We use trig functions to write equations like this in parametric form. In this case we can use the fact that , by writing:

and

You'll see that if you eliminate between these two equations you get:

and

So, using the above trig identity:

Grandad - Apr 5th 2009, 11:39 PMcheet0face
Lemme check....

Yep, my brain just exploded.