i have dout that why not we consider rays passing along principle axis in image formation by concave mirror

the rays hit the curvature normally,hence suffer no refraction

rays hit the curvature normally,hence suffer no refraction

Depending on the object location, the image could be enlarged or reduced in size or even the same size as the object; the image could be inverted or upright; and the image will be located in a specific region along the principal axis. To understand these relationships between object and image