ANGLE & IT'S TYPES (GEOMETRY)

          

              Angle 

                 & 

    it's Classification

 Vertex :

        The meeting point of two line segments or rays is called vertex.

                                        or 

          The common end point of two line segments or rays is called vertex when the two line segments or rays meet at a point.

    

Fig - 1

Fig - 2

Fig - 3

  ANGLE :

            The inclination  ( झुकाव )  or gapping between two line segments ( or rays) on meeting is called an angle.

     It can be measured in degrees (°). It can be named by its three points with vertex in the middle like

 ABC        PQR

  

Classification:

Angles can be classified as :-    

(1) Acute Angle  

 

(2)Right Angle

                                                            

(3) Obtuse Angle 

                                                             

(4) Straight  Angle

                                                             

(5) Reflex  Angle

                                                             

(6) Complete  Angle

                        

    Acute Angle :-

An angle whose measure is less than 90° is called an acute angle.

      For example; 30°, 65°, 85°, 74°, 12°   

 { 0° < acute angle <90° } 

 

 Right Angle:-

     An angle whose measure is  exact 90°  is called a right angle.

                        or 

       An angle of 90° is called a right angle.

             { right angle = 90° } 

 

 Obtuse Angle:- 

    An angle whose measure is greater than 90° but less than 180° is called an obtuse  angle.

            For example;   130°,  95°, 120°, 170°, 112°, 150°, etc.  

 { 90° <  obtuse angle < 180° }

  

  Straight  Angle:-

  An angle whose measure is  exact 180° is called a straight angle.

                                or 

    An angle of 180° is called a straight angle.  

       { straight angle = 180° }

 

 Reflex  Angle:-

   An angle whose measure is greater than 180°  but  less than 360° is called a reflex angle  

      For example;  195°,  220°, 270°, 300°,  350 ° etc 

 { 180° < reflex angle < 360° }

 

Complete  Angle:- 

    An angle whose measure is  exact 360°  is called a complete angle.

                                or 

    An angle of  360°  is called a complete angle. 

    { complete angle = 360° }

 

Fig - 1

                    

   

Fig - 2

 NOTE:  According to some mathematician , there is an existence of Zero Angle.

 Zero Angle:-

 When there is no gapping between two line segments then the angle is called zero degree.

Summary of different angles