Fused rings geometrical isomers

Decalin (bicyclo[4.4.0]decane) is the most common example of a fused-ring system. Two geometric isomers of decalin exist, as shown in Figure 3-27. In one isomer the rings are fused using two cis bonds, while the other is fused using two trans bonds. You should make a model of decalin to follow this discussion. 

Syn/anti nomenclature is mainly employed for octahedral complexes when geometric isomerism arises from the presence of a fused ring. Therefore, the syn isomer has adjacent fused rings whereas the anti isomer has opposite fused rings [5]. 

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