How to write equation using latex

Question

I am working on article writing and that's the first time that I use Latex. How to write complex equations contain cosine with latex.

Answer 1

You use

\begin{equation}
    b = \frac{1}{m}(A^T\bm{1}-W^TZ\bm{1}),
\end{equation}

to type equation (20). Other equations can be typed similarly.