Formula

[SMcNeill]

Glad you have it worked out.

I got a new ArcSin function out of it now I need to figure out what to do with a Function with 2 answers to it
Probably not acceptable to math definition of function but this one tells the whole truth of what the angle might be.

You'll never know what the angle might be. 

_ASIN(0.5)  -- this might be 30 degrees.  It might be 150.   It might be 390 degrees.   It might be 510.  Ot could be -330.  Or maybe -210....

So when you hit the _ASIN button, it tells you the first and simplest value that it can be -- 30 degrees.

You can never confer that angle back from the value alone, multiple angles all return that same sine value.