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