\documentclass{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsfonts}

\thispagestyle{empty}
\begin{document}
\[
h = \sqrt{(280\,cr)^2 - \left(\dfrac{440\,cr}{2}\right)^2} = \sqrt{30\,000\,cr^2} = 100 \sqrt{3}\,cr
\]
\end{document}
