openCV detect arc python

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Hi all! I have this Image

https://imgur.com/a/ygIAaYP

And I need do detect these 2 arcs of circumference (see the img below) because of I need to inspect the histogram region beetween these 2 arcs.

https://imgur.com/a/ILZRhaA

The problem is that i have to detect these arcs in a non-absolute way because of the object have to rotate and the area beetween the 2 arcs is not fixed.

So i need some help to check how to locate the 2 arcs..

Thank you!