A ray is a line that starts at a given point and goes off for ever in some direction. It may pass through another point as it does so. This is the same as the definition of a Ray in ordinary plane geometry, the only difference being that we know the coordinates of the points involved. The naming conventions are also the same.

Things to try

1. In the above diagram, press reset. The ray AB has an endpoint A at (53,7) and passes through point B at (53,20) on its way to infinity.
2. Drag A, B or the origin point and construct various other rays to get a feel for the concept.

See also the definition of a Ray in plane geometry.

Other Coordinate Geometry entries

• Introduction to coordinate geometry
• The coordinate plane
• Coordinates of a point
• Distance between two points

• Introduction to Lines in Coordinate Geometry
• Lines (in Coordinate Geometry)
• Rays (in Coordinate Geometry)
• Line Segments (in Coordinate Geometry)
• Midpoint of a line segment (Midpoint Theorem)
• Slope (m) of a line
• Intercept (b) of a line
• Equation of a line in slope-intercept form y=mx+b
• Equation of a line in point-slope form y=m(x-Px)+Py

• Vertical lines
• Horizontal lines
• Parallel lines
• Perpendicular lines
• Intersecting lines

• Area of a triangle (formula method)

• Print blank graph paper