In the following model, the carbon atoms are dark gray, hydrogen is cyan and oxygen is red. Note the equatorial orientation of the hydroxyl group, and the axial locations of the angular methyl groups. Unlike the rigid ring system, the eight carbon side chain is flexible and may assume many conformations.
In the following models, the carbon atoms are dark gray, hydrogen is cyan. The two carbon atoms common to both rings (ring fusion carbons) may be marked (colored blue) by clicking the designated button. At the same time, the hydrogen atoms on these carbons (called angular hydrogens) will be colored magenta. The three buttons in the last row mark certain features of cis-decalin that render it less stable than its trans isomer. The gauche orientations are not all shown together because of overlap.
trans-decalin (decahydronaphthalene)
cis-decalin (decahydronaphthalene)