Concave or concavity may refer to:
Science and technology
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Concave lens
A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), ...
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Concave mirror
Mathematics
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Concave function, the negative of a convex function
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Concave polygon
A simple polygon that is not convex is called concave, non-convex or reentrant. A concave polygon will always have at least one reflex interior angle—that is, an angle with a measure that is between 180 degrees and 360 degrees exclusive.
Polyg ...
, a polygon which is not convex
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Concave set
In geometry, a subset of a Euclidean space, or more generally an affine space over the reals, is convex if, given any two points in the subset, the subset contains the whole line segment that joins them. Equivalently, a convex set or a convex ...
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concavity of a function, determined by its second derivative
See also
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{{disambiguation, math