Diketahui f(x)=√3 cos x-sin x. Jika f(x)=k cos (x-α) dan k> 0 maka..

f(x) = a cos x + b sin x = k cos (x - ¢)
k = √(a^2 + b^2)
tan ¢ = b/a

f(x) = √3 cos x - sin x
(a, b) = (√3, -1) => dikuadran 4
k = √(√3^2 + (-1)^2) = √(3 + 1) = √4 = 2
tan ¢ = b/a = -1/√3 . √3/√3 = -1/3 √3 => tan ¢ = tan 330°

k cos (x - ¢) = 2 cos (x - 330°)