Bruh that's not how any of this works.

First off, if there's always variance, then logically by random chance sometimes you must measure exactly 90°.

Second of all, how many decimal points are you measuring too? 1? 2? 10^-23? The likelihood of measuring exactly 90° definitely goes down the more places you measure to, but A: precision is only useful up to a certain point, and B: it is never 0%.