What were the three main purposes for which Leonardo used drawing?

Though many of his inventions were impractical, Leonardo was fascinated by the inner workings of things, be they machine or man, and used his drawings to support himself throughout his life.

Explanation:

sorry if this doesnt answer it

so, not gonna do the actual thing because that's just laziness for an easy assignment like this.

but someone that has a lot of information and interesting details about is picasso. you can easily write a 500 word essay about him and how overtime his paintings of himself got more and more deformed representing that he was forgetting what he looked like and that was from memory.