Let a complex number be $w = 1 - \sqrt { 3 } i$. Let another complex number $z$ be such that $| z w | = 1$ and $\arg ( z ) - \arg ( w ) = \frac { \pi } { 2 }$. Then the area of the triangle (in sq. units) with vertices origin, $z$ and $w$ is equal to\\
(1) 4\\
(2) $\frac { 1 } { 2 }$\\
(3) $\frac { 1 } { 4 }$\\
(4) 2