Doubt

[Halflife]

CONTENTS DELETED

The author has deleted this message.

[Abhitesh]

Should be 3.
It'll difficult to balance a chair on 2 legs.

[Halflife]

CONTENTS DELETED

The author has deleted this message.

[Abhitesh]

In that case you assume that chair balances on 2 legs, which is not possible.
So it starts falling on one side till 3rd leg also touches the ground.

[Halflife]

CONTENTS DELETED

The author has deleted this message.

[Abhitesh]

Another way to look at it is following.
Take one of the legs as origin, then three legs of a chair for 2 vector. And we know that two vectors are always coplanar lying in plane(P). And you can always have a plane || to P cutting through any surface.
It is also possible for 2 legs had there been no gravity.

[Halflife]

CONTENTS DELETED

The author has deleted this message.