Hi Pritam,
Good advice from the Cap'n and Sir Quack, however, I tend to prefer a bit less than the equilateral triangle suggestions, mainly to avoid a "hole-in-the-middle" effect if you happen to be listening just in stereo with no center running.
That said, you certainly want a minimum separation of 6 feet or more to get some stereo separation and spaciousness. As others have noted, it's worth experimenting a bit based on your distance from the front speakers to the seating area with your particular room.
Regards,
Alan
