Your house, your neighborhood, and the world, in general, are filled with optical phenomena. For example, the top two images above show reflections in the flat surfaces of Hessian Lake in Bear Mountain State Park; the bottom left image is the rear-view mirror in my car. The three mirrors so far are all flat but the passenger side mirror is often convex. The bottom right mirror is the “Bean” (Cloud Gate) in Chicago’s Millennium Park. It has really complicated curves. You probably have a concave make-up mirror in your house and if you are on the lookout you are likely to see convex mirrors used to eliminate blind spots at intersections. These are all optical mirrors but you should also be on the look out for concave antenna that are used as mirrors for radio and other signals.
Just Add Math 