An angle is a figure of geometry that is formed by two rays that share the same vertex as origin. The concave adjective, which comes from the Latin word concăvus, refers, for its part, to what exhibits an inward curve.

According to DigoPaul, the idea of a concave angle is usually understood in relation to the notion of a convex angle. For this we must consider that, in the same plane, two rays that are not aligned or coincident and that share origin, always give rise to two angles: a concave angle and a convex angle. The concave angle is the widest, while the convex angle is the one with the smallest width.

To evaluate the direction of the curve exhibited by these angles, a point of view is necessary: when we say “inward”, we refer to a curve that moves away from the observer and “enters” the imaginary circle that complete the convex angle and the concave. Similarly, the convex angle has its center point more prominent than the rest, that is, it is closer to the observer and protrudes from said circle.

Concave angles, also called entering angles or reflex angles, measure more than 180 ° but less than 360 °. This means that the concave angles are never null (0 °), acute (more than 0 ° and minus 90 °), straight (90 °), obtuse (more than 90 ° and less than 180 °), flat (180 °) nor complete (360 °). Different is the case of the convex angles, which can be acute, straight or obtuse, since they measure more than 0 ° and less than 180 °.

For simplicity, to make it easy to distinguish between concave and convex angles, it is often said that concaves are those that measure more than 180 ° and that convex ones are those that measure less than 180 °. In any case, it must be clarified that 360 ° angles are perigonal or complete angles, and not concave, a feature that leaves them out of this simplified classification.

These concepts have many applications that exceed the limits of mathematics and physics, since they are used in the manufacture of various products, among which we can highlight mirrors and television screens. In the first case, convex mirrors allow the observer’s field of vision to be widened, which is why they are used in parking lots, in cars and at certain busy crossings to minimize the risk of car accidents.

Regarding television screens, in 2013 the Korean companies Samsung and LG presented the first designs based on a concave angle to the world, something that caught the eye powerfully, given that consumers had been happy for years with their flat monitors. But, far from being an arbitrary decision or the intention of establishing a passing fad, it is based on an unquestionable characteristic of our own anatomy: our eyes are curved, and their convexity is perfectly complemented by the concavity of these screens.

The use of a concave angle for the manufacture of screens has already been experimented in various cinemas, and experts say that it offers a greater degree of immersion in content. While at first the public feared that the image would be distorted by the curvature, the manufacturers maintain that this happens with flat screens, where all the points of the scene are at the same distance from our eyes, something that is not it can happen in reality.

If we look at a very wide building, the edges of our eyes will capture the image at a slightly different distance than the center, and that generates a certain distortion that is natural to our species. Therefore, the concave angle of modern televisions serves to offer a more realistic and easy to decode experience for the brain than all the previous proposals.