The Image speaks for it's self.
Point gradient formula is y - y0 = m(x-x0)
$\displaystyle y - 3 = 6 \cos \frac{\pi}{6} \left(x - \frac{\pi}{6} \right) $
For the constant b:
$\displaystyle 6 \cos \left( \frac{\pi}{6} \right)\times \frac{-\pi}{6} + 3 = - \not6 \left( \frac{\sqrt 3}{2} \right) \times \frac{\pi}{\not6} + 3 = \frac{\sqrt 3}{2} \pi + 3 $