9th Class Mathematics Related to Competitive Exam Concept of Angle in Geometry

      Introduction

This is the one of the fundamental concept of "Trigonometry". Trigonometry is the branch of mathematics which deals with the measurement of sides and angles of a triangle. In modern days, its scope has been extended and it also includes the study of polygons and circles.  

       Concept of Angle in Geometry

We know that a line is a geometrical shape which extended infinitely in both directions.

Suppose when a point P put anywhere in the above line, it will be converted into rays. These rays are responsible for the formation of an angle means "An angle is a geometrical figure made by two rays having common end point (called vertex)" these rays are called sides or arms of an angle. An angle is represented by S a symbol "<". The way to represent it put vertex in the middle.

\[\angle \text{RPO},\angle \text{SPQ},\angle \text{RPS}\] are the angles with vertex P.

The inclination of one ray to other represented by a number is called measurement of an angle. One of the most important aspect of geometry is that all the angles are between \[0{}^\circ \]and\[\text{36}0{}^\circ \] and there is no meaning of negative angle.