Lec_010, Metric Spaces, Union of open sets is an open set. (Urdu/Hindi)

This is lecture number 10 of the lecture series "Metric Spaces". In this lecture it is proved that union of any number of open sets is open in a metric space. For suggestions you may email us naveed.mathlogic@gmail.com" or message us on whatsapp number (092)03154414993. Any contributions will be welcomed.