Numerical: Find the value of sin( 31π / 3) & cos(– 1710 °) Solution: Sin( 31π / 3) = sin( 10 π + π / 3) = sin( π / 3) = √3 / 2
Cos(– 1710 °) = cos(– 1710 ° + 5 * 360 o) = cos(-1710 o + 1800 o) = cos( 90 o) = 0
Trigonometric Functions o o o o o o sin(- x) =- sin x cos(- x) = cos x tan(-x) =- tan x cosec(-x) =-cosec x sec(-x) = sec x cot(-x) =-cot x o o o o cos( π / 2-x) = sin x sin( π / 2 – x)= cos x tan( π / 2 – x)= cot x cot( π / 2 – x)= tan x o o o o cos( π / 2 + x) =- sin x sin( π / 2 + x) = cos x tan( π / 2 + x) =- cot x cot( π / 2 + x) =- tan x o o o cos( π – x) =- cos x sin( π – x) = sin x tan( π – x) =-tan x