[uvcyclotron]

If that's the case why does 1,3-dimethylcyclohexane (cis) have a plane of symmetry? Is it because the methyl groups are situated in such a way that non-planarity of the chair conformer doesn't cause a problem? You know, like if its distorted in the direction of one methyl group, it is distorted equally in the direction of the other.

Actually I am still intrigued by this thing..how can even the 1,3-dimethycyclohexane have a plane of symmetry, even if I assume both methyl groups in equatorial position (cis), then also the 3-D nature of the whole structure by itself inhibts the appearance of any kind of Plane of Symmetry..
 
Can anyone explain this, please?

[discodermolide]

I was reading Solomons a while ago when I was faced with a peculiar situation. It was the chapter on stereoisomerism and optical activity, and the section on cyclic systems.
They have described 1,2-dimethylcyclopentane and 1,3-dimethylcyclohexane to have a plane of symmetry as follows -:



I guess I have a misconception about what a plane of symmetry actually is and how to draw it on such molecules. Could someone point it out to me?

Draw them in 3d and you will recognise the answer