[1][2][3] Tangstad made her debut in 1954 in the musical South Pacific at the Central Theater, where she later worked from 1957 to 1958.

On the stage, she particularly made a name for herself as Sofia in Anton Chekhov's Platanov, Hazel in Eugene O'Neill's Mourning Becomes Electra, Helen in Shakespeare's Twelfth Night, Mrs. Krane in Kranes konditori, and Guriana in Oskar Braaten's Ungen.

[1] She also appeared in a number of films, and in 1958 she played the leading role in the film I slik en natt as a young doctor who is at the head of a rescue operation in which the children of a Jewish orphanage in Oslo are saved from the Gestapo during the Second World War.

On television, she appeared in the miniseries Nitimemordet, the series Benoni og Rosa, and two episodes of Fleksnes Fataliteter ("Visittid" 1972 and "Trafikk & Panikk" 1974).

She also provided the voice of Maid Marian in the Norwegian-language version of the cartoon Robin Hood.