I tried to patch the following formula to find a certain angle in a perpendicular triangle, using the fuction (Complex Inverse) node set to ArcTan:
(alpha) = tan-1(a/b) =t an-1(1/2) = 26.57°

But it outputs 0.5236 instead.
I’m not very good in trigonometry, so I could need some explanation here ;)

we have two different ways to express angles, none of these is “degrees” unfortunatly.

in far the most cases we describe them as fractions of full cycles.

but in some special low level nodes, which are really thought to be direct implementations of math functions, we decided to use the unit radian (rad on your calculator), because this is the unit which is used in most other languages as well.

in this way it is easier to implement algorithms which are already formulated in a peace of code (in one of these tyical textual languages).

here are some modules for the convertions between

cycles

degrees

radians
and an extra module for Pi.

in your case take the Degrees (Value Radians) to convert from Radians into Degrees.