How to Re-write Function as Unit Step Function Write the function given by: $cos(t)$, $t ∈ [0, 2π)$ and $0$ otherwise, in terms of unit step functions.
This step is at the beginning of solving a Laplace Transform, which I can do, I just don't understand this initial step. 

@Dr. MV An alternative solution, with the same definition of $u$ (or as u).
$$f(t)=\cos(t)u(t)u(2\pi-t)=\begin{cases}\cos(t),&t\in [0,2\pi)\\\\0,&\text{elsewhere}\end{cases}$$
