What is the Difference Between Convex and Concave?

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  • Written By: Malcolm Tatum
  • Edited By: Bronwyn Harris
  • Last Modified Date: 25 November 2018
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Convex and concave are terms that are used to define two different types of curvatures. While both convex and concave relate to some type of curve, they are never used to refer to the same type of curve. However, it is usually possible to classify just about any incidence of curve as either convex or concave.

In order to understand the difference between convex and concave curvatures, it is first necessary to define each term. Convex relates to a curvature that extends outward. The curve can occur at any point along the surface of any object. Perhaps the classic example of a convex curve would be the surface of a ball or sphere.

By contrast, concave indicates the presence of a curve that extends inward rather than outward. When an object is concave in nature, the appearance is a section between two points that may appear to be hollowed out. A good example of a concave object would be a bowl or plate.

Curved surfaces of both types are commonly employed as a means of achieving a particular effect. For example, soft contact lenses are shaped into a convex configuration in order to provide a comfortable but snug fit for the shape of the eye. The curved surface of the lens makes inserting the contacts an easier task than the older flat lenses, while also making it possible to wear the curved lenses for a longer period of time.


Concave surfaces are found with all types of hollow ware. Along with plates and serving bowls, spoons and forks also exhibit a concave construction that helps the utensil be useful in eating and various tasks in food preparation. When it comes to human form, a concave appearance to the stomach area is often considered to be physically attractive in both genders.

Combinations of convex and concave angles are sometimes employed to create interesting visual impact. For example, funhouse mirrors usually employ both concave and convex curves along the surface of the mirror to achieve a specific type of visual distortion. The end result of using this combination of curves has proven to be a source of amusement for carnival goers for well over a hundred years.


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Post 14

So does a concave mirror magnify the object?

Post 12

I'm confused about the difference between convex and concave given your examples. You say that "A good example of a concave object would be a bowl or plate." Yet later, you name another convex item: the contact lens. "Soft contact lenses are shaped into a convex configuration," but a contact lens appears to be the shape of a bowl (to me, that is). Can you clarify more about the differences? We are studying parabolas in class and I wanted to use the proper term: convex or concave. I think it's concave, but given that a parabola can look like a bowl or a contact lens, now I'm confused. Thanks for your clarification.

Post 10

Misread your question. All triangles are convex, so there are no concave angles inside them.

Post 7

answer 1. for anon 28490: sum of interior angles of any triangle must be 180 degrees.

Post 2

How do you test your tools before applying the product to them? Need to know how to react to them first...ty

Post 1

I need to know about the sum of the interior angles of a triangle?

Will a concave that is not convex always have an interior angle with a measure that is greater than 180 degrees?

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