For particle \( P \) revolving round the centre \( O \) with radius of circular path \( r \) and angular velocity \( \omega \), as shown in below figure, the projection of \( OP \) on the \( x \)-axis at time \( t \) is:
\( x(t) = r \cos(\omega t) \)
\( x(t) = r \cos\!\left(\omega t + \dfrac{\pi}{6}\right) \)
\( x(t) = r \cos\!\left(\omega t - \dfrac{\pi}{6}\,\omega\right) \)
\( x(t) = r \sin\!\left(\omega t + \dfrac{\pi}{6}\right) \)