Check my Z transform problem solution

[tronix]

Hi all
I needed to calculate Inverse Z of:

H(z)=1/(1-2r*cosΦ*/z+r²/z²)

I calculated the answer ro be : r^n*sin(n+1)Φ/sinΦ
Whereas Answer given in a text is : r^n*cos(n+1)Φ/cosΦ

I need the right the result to progress.
Can someone confirm the right answer?

Regards
tronix

 

[mondunno]

Z transform problem

which book u referred?

ur answer is right

( r^n*sin[n+1]Φ/sinΦ )u[n+1] given roc to be |z|>r

whats the roc mentioned in the book?

 

[tronix]

Z transform problem

Hey mondunno
Yes I checked and found the result to be correct (there was an error in the text)
Thanks a lot

Regards
tronix