Draw the structures of the geometrical isomers of $[Fe(NH_3)_2(CN)_4]^-$.

(N/A) The complex $[Fe(NH_3)_2(CN)_4]^-$ is an octahedral complex of the type $[MA_2B_4]$.
In the $cis$-isomer,the two $NH_3$ ligands are adjacent to each other (at $90^{\circ}$ angle).
In the $trans$-isomer,the two $NH_3$ ligands are opposite to each other (at $180^{\circ}$ angle).
The structures are as follows:
$cis$-isomer: The two $NH_3$ groups are at $90^{\circ}$ to each other.
$trans$-isomer: The two $NH_3$ groups are at $180^{\circ}$ to each other.