1) The surface area of a cell in a honey comb is:

$\displaystyle S = 6hs + \frac{3s^2}{2}\left(\frac{\sqrt{3} - \cos(\theta)}{\sin(\theta)}\right)$

where h and s are positive constants and theta is the angle at which the upper faces meet the altitude of the cell. Find the angle theta ($\displaystyle \pi/6 <= \theta <= \pi/2$) that minimizes the surface area S.