The "Standard trigonometric functions" is right, but the "x is in radians" part is true just for the last three functions ( , , ). The argument of the , , functions are not angles (neither in degrees, neither in radians), but numbers. More than this, the argument of the and functions must be between -1 and 1. The result of the , , functions are indeed expressed into radians.Standard trigonometric functions. x is in radians.
Eg the will give an error, because as I said, the argument of the Asin (and Acos) function(s) must be between -1 and 1. works well.
Please check and if I'm right, fix the help.