Maybe it is not accurate at all, but it looks very accurate for me. I'm making a scientific calculator for my portfolio, and I found an interesting phenomenon.
Because computers store decimals not accurately but approximately, I thought that asin(sin(30rad)) wouldn't give 30rad, and sqr(sqrt(7)) wouldn't give 7, etc..
However, it seems that every kind of calculations like above gives an accurate result. (I used cmath header of c++, and I checked that python math modules also gives the same)
This consequence seems even arcane to me. Does the computer really store those non-repeating deicmals? or is it just a matter of implementation of math libraries, like substituting a special symbol for them?