In the Greek deductive geometry of Euclid's Elements, a general line (now called a curve) is defined as a "breadthless length", and a straight line (now called a line segment) was defined as a line "which lies evenly with the … See more

Vectors
The vector equation of the line through points A and B is given by $${\displaystyle \mathbf {r} =\mathbf {OA} +\lambda \,\mathbf {AB} }$$ (where … 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 … See more

• Affine transformation
• Curve
• Distance between two parallel lines See more

Linear equation
Lines in a Cartesian plane or, more generally, in affine coordinates, are characterized by linear equations. More precisely, every line See more

Ray
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 … See more

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