hardwood flooring in two rooms not parallel
Just taper a couple of pieces of flooring to distribute the adjustment across a wider area.  Preferably this would be done in a doorway, as IronEagle notes.  Trim them on the female side of a tongue/grooved board, because...:

I learned this lesson the hard way:  It's worth getting a bit or blade (router?  dado?) that you can use to reconstruct the groove on the trimmed side, so your boards still fit tightly together.