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
If a is vector OA … 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
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Linear equation
Lines in a Cartesian plane or, more generally, in affine coordinates, are characterized by linear equations. More precisely, every line $${\displaystyle L}$$ (including vertical lines) is the set of all points whose See more

Ray
Given a line and any point A on it, we may consider A as decomposing this line into two parts. Each … See more

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