Collinear

Three or more points are said to be collinear if they lie on the same straight line.

Collinear is a high school-level concept that would be first encountered in a geometry course covering plane geometry.

Prerequisites

A line is the infinite extension in both directions of a line segment, giving the path of shortest distance between two points in Euclidean space.

Classroom Articles on Plane Geometry

	Acute Angle	Midpoint
	Altitude	Obtuse Angle
	Angle	Parallel
	Area	Perimeter
	Circle	Perpendicular
	Circumference	Pi
	Complementary Angles	Plane Geometry
	Diameter	Point
	Geometric Construction	Radius
	Golden Ratio	Supplementary Angles
	Golden Rectangle	Triangle Inequality
	Hypotenuse

Classroom Articles on Geometry (Up to High School Level)

	Cone	Octahedron
	Congruent	Parallelogram
	Convex Hull	Pentagon
	Cross Section	Platonic Solid
	Cube	Polygon
	Cylinder	Polyhedron
	Decagon	Polytope
	Dodecagon	Prism
	Dodecahedron	Pyramid
	Equilateral Triangle	Quadrilateral
	Geometry	Rectangle
	Hendecagon	Regular Polygon
	Heptagon	Right Triangle
	Hexagon	Similar
	High-Dimensional Solid	Solid Geometry
	Hypercube	Sphere
	Hyperplane	Square
	Hypersphere	Surface
	Icosahedron	Surface Area
	Isosceles Triangle	Tetrahedron
	Linear Function	Trapezoid
	Nonagon	Triangle
	Octagon	Volume