Answer:
When light impacts a plane mirror, the light ray is reflected with the same angle as the incident light ray.
For the curved mirrors, like the convex mirror, the normal surface of the mirror is not plane, so the angles change, for example, a light ray that includes horizontally in a curved part (not in the middle, a little bit above it for example) will impact a curved surface, and the reflected light ray will have a direction that "goes away" from the center of the mirror.
This means that those mirrors produce an image like a plane mirror right in the middle, and as you go to the sides, the image starts to be dilated.
