答案1
\documentclass{article}
\usepackage{graphicx}
\usepackage[margin=1in]{geometry}
\begin{document}
\centering
\includegraphics[angle=90,width=\linewidth,height=.499\textheight,keepaspectratio]{example-image-golden-upright}\vfill%
\includegraphics[angle=90,width=\linewidth,height=.499\textheight,keepaspectratio]{example-image-10x16}%
\end{document}