The incentre of the triangle with vertices $(1, \sqrt{3}), \; (0,0)$ and $(2, 0)$ is :
( A ) $(\frac{2}{3}, \frac{1}{\sqrt{3}})$
( B ) $(\frac{2}{3}, \frac{\sqrt{3}}{2})$
( C ) $(1, \frac{\sqrt{3}}{2} )$
( D ) $(1, \frac{1}{\sqrt{3}} )$