Ch - Geometry Basics

Points 

  • It is a position or location on a plane surface, which are denoted by a single capital letter.
  • It is denoted by a dot. 
  • Capital letters are used to name a Point.

Line Segment

  • It is a part of a line with the finite length and 2 endpoints.

  • The points E and F are called the endpoints of the segment. 
  • It is named as: line segment  EF or line segment FE

Line

  • It is made up of infinitely many points with infinite length and no endpoint. 
  • It extends indefinitely in both directions. 
  • Single small alphabet is used to name a line.

Ray

  • It is a part of a line with one starting point whereas extends endlessly in one direction. 

What are Angles? 

  • A figure formed from 2 rays which share a common endpoint is called Angle. 
  • The rays forming the angle are known as its arms or sides. 
  • The common endpoint is known as its vertex.

Naming an Angle
  • While naming an angle the letter depicting the vertex appears in the middle. 
  • An angle can also be named just by its vertex.



An angle is also associated with 3 parts
1. Interior - 

  • It refers to the inside/inner area.
  • Point P lies in interior of the angle

2. Angle/boundary -

  •  It refers to the arms of the angle.
  • Point B lies on the angle

3. Exterior - 

  • It refers to the outside / outer area. 
  • Point R and Q lies in exterior of the angle 

The above angle can also be named as ∠BOA or ∠AOB or ∠B

Intersecting Lines

  • The two lines that share one common point are called Intersecting Lines.

  • This shared point is called the point of intersection.
  • Here, line q and p are intersecting at point O.

Parallel Lines

  • Two or more lines that never intersect (Never cross each other) are called Parallel Lines.