CGMutablePath add arc method not working as expected?

the method in question:

newPath.addArc(center: CGPoint(), radius: 80 , startAngle: 0, endAngle: anAngleInRadians, clockwise: false)

https://developer.apple.com/documentation/coregraphics/cgmutablepath/2427140-addarc

this path is far too short. It is definitively NOT reaching the angle I am setting it to. In fact it's almost as if it wants to get the angle in degrees, but THAT is far too much. the docs say it works in radians, but I can confirm that radians is not giving the correct output. hard coding the end angle to 1 radian gives you an arc that is just about 11 degrees. which is not correct.


so I have a goldilocks problem, that should not be.

Anyone know if the Arc Method in CGMutablePath is known to be broken?