Find length and angles in an image

how to get the size of each side in an image if the image has both straight line and curved lines,
i want to find

  1. number of sides and their length (if any side has curved/arc shape then their radius )
  2. number of corner and their angles

if the image has all sides as straight line then i have calculated all above but in case image has mixture of straight line and curved line then unable to find.