Diequatorial cis-1,3-Dimethylcyclohexane
This is the cis-stereoisomer of 1,3-dimethylcyclohexane. Both methyl groups (green) are equatorial in this conformation. The ring-flip conformation, with both methyl groups axial, is much less stable (see below). The cis-isomer is more stable than the trans-isomer, which has one methyl group axial and one equatorial in both conformations (see Problem 6.11).
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Diaxial cis-1,3-Dimethylcyclohexane
Both methyl groups (green) are axial in this conformation of the cis-stereoisomer. There is a very large amount of steric strain due to the interaction of these two groups which have a 1,3-diaxial relationship. You can see how the methyl groups bend away from each other so that their bonds to the ring are not parallel in order to relieve some of this steric strain. The ring-flip conformation, shown above, is much more stable because both methyl groups are equatorial.