Which are two of the three theatres at the National Theatre?

The Olivier Theatre and Dorfman Theatre are indeed two of the three main theatres at the National Theatre in London. The Olivier Theatre is the largest of the three and is named after the distinguished actor and director Laurence Olivier, who was instrumental in the establishment of the National Theatre. The Dorfman Theatre, previously known as the Cottesloe Theatre, is a smaller venue that focuses on innovative and experimental productions, providing a more intimate setting for performances.

Both theatres are central to the National Theatre’s mission of presenting a wide range of works, from classic plays to modern performances, appealing to diverse audiences. The inclusion of both in your answer highlights a solid understanding of the National Theatre's offerings and its dedication to theatre as an art form.