TRIGONOMETRY-(RATIOS,IDENTITIES AND HEIGHTS AND DISTANCES)
TRIGONOMETRY (RATIOS, IDENTITIES AND HEIGHTS AND DISTANCES) Trigonometry deals with the study of triangles, the measurement of their sides, angles and the various relations which exist between them. Angle: An angle, in trigonometry, is formed by the rotation of a ray in a plane around the end point. In the above figure, OA is the initial position and OB is the final position of the ray. Positive and Negative Angles: If the rotation of the ray OA about 'O' is in the anticlockwise direction, then the angle AOB is positive and if the ray rotates in the clockwise direction, the angle made is considered as negative. Quadrants: The concept of quadrants was discussed in the chapter Co-ordinate Geometry in detail. We now summarize this concept diagrammatically. Systems of Measurement of Angles: Initially, we understand the division of a right angle. 1 right angle=90^o (ninety degrees) 1^o =60' (Sixty minutes) 1'=60" (Sixty seconds)