Flat mirrors are typically found on your driver’s side and have no curvature or radius.
Convex mirrors are typically found on your passenger’s side. Depending on the vehicle, convex side view mirrors can be found with different curvatures and radiuses.
Place a flat edge on your mirror’s surface. If there are gaps on the outer sides, your mirror is convex. Another good way to tell if your mirror is convex is by the presence of the “objects in mirror are closer than they appear” statement.