She sang 'We Found Love.'
Yes she was.
Rihanna was never on the X Factor.
Rihanna has appeared on the X Factor a few times as a guest star.
no he's not
Cannonball by Damien Rice.
They sang 'unfaithful' by Rihanna.
The A Team by Ed Sheeran.
Amaro
I'm not 100% sure but Simon is the person who gets the celebrities to guest star on x factor, and rihanna was on the x factor very recently so i would say yes.
Big girls dont cry by fergie
The X Factor - 2011 was released on: USA: September 2011
Cher Lloyd sang Whip My Hair, The Clapping Song and Stay on The X Factor Tour 2011.