TRIGNOMETRY FUNCTIONS 2.ANGLES
3.2 ANGLES
Trigonometry functions are measured in terms of radian for a circle drawn in XY plane. Radian is nothing but the measure of an angle just like a degree. The difference between the degree and radian is;
Degree:If rotation from the initial side to terminal side is (1/360)th of revolution, then the angle is said to measure 1 degree.
1 degree=60minutes
1 minute=60 second
Radian: If an angle is subtended at the center by an arc of length ‘l’ and then the angle is measured as radian. Suppose
θ = Length of the arc/radius of the circle.
θ = l/r
Relation between Degree and Radian:
2π radian=360°
Or
π radian=180°
Where π = 22/7
TABLE FOR DEGREE AND RADIAN RELATIONS
Consider a unit circle with centre at the origin(0,0).Let P(x,y) be any point on the circle.Let angle AOP be θ
radians.Then we define cos θ = x and sin θ = y.
So we define cos θ as x coordinate of a point on a unit circle with centre at the origin and θ the angle between positive x axis and the radius to the point.And sin θ is the y coordinate of the same.
Consider the following:
