Sine
From specialfunctionswiki
The sine function, usually written $\sin$, is the solution of the second order initial value problem $y=-y;y(0)=0$.
Properties
Proposition: $\sin(x) = x \displaystyle\prod_{k=1}^{\infty} \left( 1 - \dfrac{x^2}{k^2\pi^2} \right)$
Proof: proof goes here █
