Basic Geometrical Concepts

Fundamental concepts of Geometry

Point

It is an exact location. It is a fine dot which has neither length nor breadth nor thickness but has position i.e., it has no magnitude. It is denoted by capital letters A, B, C, O etc.

Line segment

The straight path joining two points A and B is called a line segment

Ray

A line segment which can be extended in only one direction is called a

Line

When a line segment is extended indefinitely in both directions it forms

Collinear points

If two or more points lie on the same line, then they are called collinear points.

Non-collinear points

Points which do not lie on the same line are called as non-collinear points.

Example:

E, F, G, H, I

Intersecting lines

Two lines having a common point are called intersecting lines. The common point is known as the point of intersection.

Concurrent lines

If two or more lines intersect at the same point, then they are known as concurrent lines.

Plane

A plane is a surface such that every point of the line joining any two points on it, lies on it.

Example:

Surface of a smooth wall, surface of a paper.