drop the LS == that is checking for equality, your output will be named as given in the output line
use sqrt ... not sure if ^0.5 works in all places... but be safe.
why don't you split stuff and do the calculations in baby steps to ensure that each component works?
you can then delete the intermediate steps or combine them into one smokin' one-liner if the pieces work.
PS move this to Spatial Analyst it has nothing to do with coordinate reference systems