1. ## Cosine fixpoint

Is the cosine fixpoint (the solution to the equation $x=\cos x$) rational or irrational, and is it possible to prove it?

2. ## Rational or irrational

Hello espen180
Originally Posted by espen180
Is the cosine fixpoint (the solution to the equation $x=\cos x$) rational or irrational, and is it possible to prove it?
I can't imagine that it could possibly be rational, but I have no idea how you might set about proving it!