This expansion comes from the Taylor expansion of arctan, computed at x = 1. It’s also called the Leibniz Series. Advertisements Continue reading That’s a pumkin but it’s also π!
So, when I saw the following post from Saturday morning breakfast cereal, I remembered proving that by using Fourier series. Curious as to how many other proofs exist, I searched around and found A LOT of them. Check here and here. Some of them have really clever arguments. 😀 Continue reading π, why do you pop up everywhere?