Definitions
Line
A length with no breadth or thickness, extending in two opposite directions without end.
Line Segment
A part of a line that is bounded by two distinct end points.
Ray
A part of a line that starts at a particular point and extends infinitely in one direction.
Angle
Formed by two rays (or line segments) that meet at a common endpoint called the vertex.
Vertex
The common endpoint where two or more rays or line segments meet to form an angle.
Types of Lines
In geometry, lines can be categorized based on their characteristics and relationships with other lines. Key types include parallel lines, perpendicular lines, and intersecting lines.
Parallel Lines
Parallel lines are two or more lines in a plane that do not intersect or touch at any point, no matter how far they are extended. They have the same slope.
Perpendicular Lines
Perpendicular lines are lines that intersect at a right angle (90 degrees). Their slopes are negative reciprocals of each other when plotted on a Cartesian plane.
Intersecting Lines
Intersecting lines are lines that cross each other at a point. They share a common point known as the point of intersection.
Types of Angles
Angles can be described based on their size or the measure in degrees. Common types include acute, right, obtuse, straight, reflex, and full angles.
Acute Angle
An acute angle is an angle that is greater than 0 degrees and less than 90 degrees.
Right Angle
A right angle is an angle that measures exactly 90 degrees.
Obtuse Angle
An obtuse angle is an angle that is greater than 90 degrees but less than 180 degrees.
Straight Angle
A straight angle is an angle that measures exactly 180 degrees and forms a straight line.
Reflex Angle
A reflex angle is an angle that is greater than 180 degrees but less than 360 degrees.
Full Angle
A full angle is an angle that measures exactly 360 degrees.
To remember :
Lines can be of several types, such as parallel, perpendicular, and intersecting, each with unique characteristics and geometric relationships. Angles, formed by the intersection of lines or line segments, are categorized by their degree measures, such as acute, right, obtuse, straight, reflex, and full angles. Understanding the nature of lines and angles is fundamental for deeper exploration in geometry.