Find the rectangular coordinates for the point given in polar coordinates as $(21,\frac{\pi }{6})$.

$(\frac{21}{2},\frac{21}{2})$

$(21\sqrt{3},\frac{21}{2})$

$(\frac{21\sqrt{3}}{2},-\frac{21}{2})$

$\(\left\)(\(\frac{21\sqrt3}{2}\),\(\frac{21}{2}\]\right\))$