To design a musical well, a designer needs to be versed in the traditions and techniques of music. Just like math, our work employees the principles of physics daily. This is especially true when engineering our sets or in designing lighting. A knowledge of physics also allows us to use a richer variety of materials in our work. Especially these days where we tend to employ elaborate special effects in our work, we need to be more and more knowledgeable about chemicals and their interaction with the human body.
Dance provides insight into how the human body moves.
An effective design will allow humans to fully interact physically. A knowledge of English is no longer enough to succeed in our current economic environment. In school I studied French. BUT many Russian words come from English or similar roots. Words in Russia for Theatre, Circus, Ballet, Stop are almost the same as our English words.