I doubt that many of us remember our high school geometry class fondly. For most, geometry was a difficult topic, detached from practical life, and the first time we encountered formal proofs and deductive reasoning.
Constructing mathematical proofs starts from assumed facts, followed by a series of statements that ultimately justify a theorem. This often seemed like Greek to me (and not just because the ancient Greeks invented the concept). But mathematical proofs are rigorous and powerful. The classic example is Pythagoras’ theorem, which tells us that for all right-angled triangles, the square of the hypotenuse is equal to the sum of the squares of the other two sides: x2 + y2 = z2.
