Thread: Parametric 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!

Hello cheet0face

Originally Posted by cheet0face

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!

There 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

Lemme check....

Yep, my brain just exploded.