Undefined for argument domain: arccos(.78) with complex numbers enabled, degree mode

[Robert Fromm]

Typing in arccos(.78) shows error undefined for argument domain when complex numbers are enabled (Settings → Behaviour → Enable complex numbers) und degree mode enabled.

arcsin(.78) also generating error.

arccos(.780000000001) no error → 38.7°

I hope you can reproduce the bug.

Version 0.12, on Windows 10 64bit, verified on two maschines

[Tey']

Duplicate of #781.

[Tey']

It has been fixed in trunk already, you can try the development builds if you need the fix.