Why wasn't the art technique of perspective used during the middle ages?

The use of perspective wasn't used during the Middle Ages because that time period was ending (5th to 15th century) when the Renaissance was just beginning (it ran from the 14th to 17th centuries) and the technique wasn't developed until the 15th century, and wasn't as popular into later on when it was more studied and the technique was more used in pieces and developed.

Very true. in today’s age anything is possible.

What instrument plays together with the orchestra in this excerpt : 35? answer: clarinet