Sin2pieover13plus cos squared pie over 13 equals.
First off, it's "pi" not "pie."
sin 2pi/13 + cos^2 pi/13
cos^2 pi/13 = (1 + cos 2pi/13)/2
so we have
sin 2pi/13 + (1 + cos 2pi/13)/2
Hmmm. Is there somewhere in particular we're going with this?