\begin{equation*}
\begin{array}{rc@{}c}
& \multicolumn{2}{l}{\, \, \, 1+\frac{1}{2}x^2 +\frac{5}{24}x^4-\dotsb} \vspace*{0.12cm} \\ \cline{2-3}
\multicolumn{1}{r}{1-\frac{1}{2!}x^2+\frac{1}{4!}x^4-\dotsb \hspace*{-4.8pt}} & \multicolumn{1}{l}{ \hspace*{-5.6pt} \Big) \hspace*{4.6pt} 1} \\
& \multicolumn{2}{l}{\, \, \, 1-\frac{1}{2!}x^2+\frac{1}{4!}x^4-\dotsb} \vspace*{0.12cm} \\ \cline{2-3}
& \multicolumn{2}{l}{\, \, \, \phantom{1{}-{}} \frac{1}{2!}x^2-\frac{1}{4!}x^4+\dotsb} \\
& \multicolumn{2}{l}{\, \, \, \phantom{1{}-{}} \frac{1}{2!}x^2-\frac{1}{\left(2!\right)^2}x^4+\dotsb} \vspace*{0.12cm} \\ \cline{2-3}
& \multicolumn{2}{l}{\, \, \, \phantom{1{}-{}\frac{1}{2!}x^2{}-{}} \frac{5}{24}x^4-\dotsb}
\end{array}
\end{equation*}