Pythagoras discoverd by stretching out two strings that to create the interval of a you need to play the second string using a ratio of 2: 1

The linear perspective changed the quality of art because it gave art a sense of reality. it gave the illusion that the background and surroundings were actually close and/or far and a sense of depth. linear perspective change the quality of art following its birth the renaissance period as they want the art to be more realistic and they believe one way to achieve it is to use the method of linear perspective. it uses the principle of math to realistically portray space and depth in art. 

Idk but maybe a camera?

Answerminuet;

Well if some words are like big you could say enormous .just make them sound more egxarreted