Re: Sine and Cosine Accuracy

[David Daney]

Dave Korn wrote:

" Identities such as
            sin(x)^2 + cos(x)^2 === 1
  are only valid when 0 <= x <= 2*PI"

It's been a while since I studied math, but isn't that particular 
identity is true for any x real or complex?

David Daney,