Question

What is the purpose of a proof in Geometry? What is structure of a proof in Geometry?​

Answer 1

Geometry (like any other branch of math) starts from a set of statements that we assume to be true, which we call axioms.

Then, we declare some rules that allow us to deduce true things from true things. For example, syllogism is one of this rules. So, if we know that $A$ is true, and it is also true that $A\implies B$, then we're allowed to deduce that $B$ is true as well.

So, the purpose of a proof is to show that a certain statement is true.

In its structure, you'll always start from some true facts, and you'll deduce new true facts by using allowed deductive methods.