I’m not sure if I’m missing something here…

I’m trying to find the xy values of an arc so I’m using the function math.cos()

in this case I have a Constant Chop with a value of 180 connected to an expression Chop using math.cos(me.inputVal)

which by my maths should result in -1, but I’m actually getting -0.5985,

I get the same result using the Function Chop - what am I missing?