In the Greek deductive geometry of Euclid's Elements, a general line (now called a curve) is defined as a "breadthless … See more

Lines in a Cartesian plane or, more generally, in affine coordinates, are characterized by linear equations. More precisely, every line (including vertical lines) is the set of all points whose coordinates (x, y) satisfy a … See more

The vector equation of the line through points A and B is given by (where λ is a scalar).
If a is vector OA and b is vector OB, then the equation of the line can be written: .
A ray starti… See more

In modern mathematics, given the multitude of geometries, the concept of a line is closely tied to the way the geometry is described. For instance, in analytic geometry, a line in the plane is often defined as t… See more

Given a line and any point A on it, we may consider A as decomposing this line into two parts. Each such part is called a ray and the point A is called its initial point. It is also known as half-line, a one-dimensional half-space. … See more

• Affine transformation
• Curve
• Distance between two parallel lines
• Distance from a point to a line… See more

• "Line (curve)", Encyclopedia of Mathematics, EMS Press, 2001 [1994]
• Equations of the Straight Line at Cut-the-Knot See more