PI in Mechanical
 

Would like to use PI in a formula for a Magnitude in Analysis settings details.
PI the constant is not recognised by ANSYS so have entered 'acos(-1)' for PI instead.
OK so far, but instead of PI (in radians), Mechanical says PI is 180 in the calculation.
Anyone know how to get around this besides from entering a truncated explicit value for PI manually please?

I'd already set Units in Mechanical for radians instead of degrees with no affect, but once I'd deleted the tree branch and redone it from scratch the correct result in radians appeared.
Hope this resolution helps others.