Subjects
Grades
Straight Lines and Half-Planes
Concept sheet | Mathematics
Secondary
4
Table of contents
In geometry, a straight line is a line formed by an infinite number of aligned points.
A straight line represented in a Cartesian plane can be horizontal, vertical, or oblique.
A half-plane represents a portion of a plane on one side of a straight line dividing the plane.
A half-plane therefore represents one of the two sections bounded by a straight line in a Cartesian plane. It is actually the graphical representation of the solution set of a first-degree inequality with two unknowns.
The shaded area on the graph below represents a half-plane:
Using these terms, it is possible to find relationships between points and lines in a Cartesian plane.
- The Distance Between Two Points in a Cartesian Plane
- The Midpoint of a Segment
- The Slope of a Line
- Forms of a Linear Equation
- The Equation of a Line From the Coordinates or Slope
- The Relative Position of Two Straight Lines
- The Equations of Parallel or Perpendicular Lines
- The Distance From a Point to a Line on a Cartesian Plane
- The Distance Between Two Parallel Lines
- The Graph of a Straight Line
- Proof in Analytical Geometry