Curves

legal limit of an immovable real estate property

thumb|300px|right|Subtangent and related concepts for a curve (black) at a given point P. The tangent and normal lines are shown in green and blue respectively. The distances shown are the ordinate (AP), tangent (TP), subtangent (TA), normal (PN), and subnormal (AN). The angle φ is the angle of inclination of the tangent line or the tangential angle. In geometry, the subtangent and related terms are certain line segments defined using the line tangent to a curve at a given point and the coordinate axes. The terms are somewhat archaic today but were in common use until the early part of the 20t

shortest paths on a bounded deformed sphere-like quadric surface

220px|right|thumb|A horosphere within the Poincaré disk model tangent to the edges of a [[hexagonal tiling cell of a hexagonal tiling honeycomb]] thumb|Apollonian sphere packing can be seen as showing horospheres that are tangent to an outer sphere of a [[Poincaré disk model]] In hyperbolic geometry, a horosphere (or parasphere) is a specific hypersurface in hyperbolic n-space. It is the boundary of a horoball, the limit of a sequence of increasing balls sharing (on one side) a tangent hyperplane and its point of tangency. For n = 2 a horosphere is called a horocycle.

mathematical equation

growth function exhibiting a singularity in a finite time

thumb|right|214px|A tacnode at the origin of the curve defined by (x^2+y^2-3x)^2 - 4x^2(2-x) = 0.

integral of curvature along a curve taken with respect to arc length

parameter (and formula) to describe stability of grains in flowing water

Unsolved geometry problem about planar regions

method of spatial referencing

curve created by a geometric operation

geometrical problem involving a sliding rod driven by a crank