Trigonometric functions
MEASUREMENT OF ANGLES 1. Angle: The measurement of an angle is the amount of rotation from the initial side to the terminal side. 2. Sense of an Angle: The sense of an angle is +ve or –ve based on whether the initial side rotates in the anti- clock-wise or clockwise direction to get the terminal side. System of measuring angles There are three systems of measuring angles such as (i) Sexagesimal system (ii) Centisimal system (iii) Circular system 4. In sexagesimal system, we have 1 right angle = 90° 1° = 60' 1' = 60" 5. In centasimal system, we have 1 right angle = 100g 1g= 100' 1' = 100" 6. In circular system, the unit of measurement is radian Radian: One radian is the measure of an angle sub- tended at the centre of a circle by an arc of length equal to the radius of the circle. Notes (i) When an angle is expressed in radians, the word ra- dian is omitted. (ii) Since 180° = pi radian = 22/(7×180)radian =0.01746 radian...
