(sin³x-2sin²x+1)/(sin x-1)
=(sin³x-sin²x-sin²x +1)/(sin x-1)
=[(sin³x-sin²x)-(sin²x -1)]/(sin x-1)
=[ sin²x(sin x-1)- (sin x-1) (sin x+1)]/(sin x-1)
=(sin x-1)( sin²x-sinx-1) /(sin x-1)
=sin²x-sinx-1
(sin³x-2sin²x+1)/(sin x-1)
=(sin³x-sin²x-sin²x +1)/(sin x-1)
=[(sin³x-sin²x)-(sin²x -1)]/(sin x-1)
=[ sin²x(sin x-1)- (sin x-1) (sin x+1)]/(sin x-1)
=(sin x-1)( sin²x-sinx-1) /(sin x-1)
=sin²x-sinx-1