Detect an arc from an image contour or edge
You can do it this way:

Convert the image to edges using canny filter.
Make the image binary using threshold function there is an option for regular threshold, otsu or adaptive.
Find contours with sufficient length (findContours function)
Iterate all the contours and try to fit ellipse (fitEllipse function)
Validate fitted ellipses by radius.
Check if detected ellipse is good fit - checking how much of the contour pixels are on the detected ellipse.
Select the best one.

You can try to increase the speed using RANSAC each time selecting 6 points from binarized image and trying to fit.
I am trying to detect arcs inside an image. The information that I have for certain with me is the radius of the arc. I can try and maybe get the centre of the circle whose arc I want to identify.
Is there any algorithm in Open CV which can tell us that the detected contour ( or edge from canny edge is an arc or an approximation of an arc)
Any help on how this would be possible in OpenCV with Python or even a general approach would be very helpful
Thanks