Leibniz's Formula for Pi/Lemma

Lemma
This holds for all real $t \in \R$.

Proof
From Square of Real Number is Non-Negative, we have that:
 * $t^2 \ge 0$

for all real $t$.

So $- t^2 \le 0$ and so $- t^2 \ne 1$.

So the conditions of Sum of Geometric Sequence are satisfied, and so the above argument holds for all real $t$.