# Lemniscate locus

1. Jun 6, 2009

### ronaldor9

Hello from the book I am reading it defines the lemniscate as the locus for which the product of the distances r1 and r2 with the coordinates x= a and x= -1 and y= 0 has the constant value of a2.

I went about deriving the equation in polar coordinates from this locus, however I do not get the correct equation when the locus is defines as r1 x r2 = a2 but when r1 x r2 = a the correct equation is arrived at.

Is this simply a typo on behalf of the author?

Last edited: Jun 7, 2009
2. Jun 7, 2009

### tiny-tim

Hello ronaldor9!

(try using the X2 and X2 tags just above the Reply box )
erm what's the difference?

3. Jun 7, 2009

### ronaldor9

I went about deriving the equation in polar coordinates from this locus, however I do not get the correct equation when the locus is defines as r1 x r2 = a2 but when r1 x r2 = a the correct equation is arrived at.

FIXED thanks!