answered about 21 months ago by opera
The National Ballet company has large studios. They are sometimes empty in the evening. Ngo 11 Nui Truc streett - just down the road from the Australian Embassy.
Also check the Hanoi International Women's Club book 'the Hanoi Guide'. It has the name of the ballet school here. (western woman) You can buy the book at the Bookworm - 25A Ngo Van So across from Tonkin Restaurant.
The housing compound at the south end of West Lake (Thuy Que ???) has a small yoga room with mirrors,.