$
\text{Gegeben:}\\\text{Hypotenuse} \qquad c \qquad [m] \\
\text{Kathete}\qquad b \qquad [m] \\
\\ \text{Gesucht:} \\ \text{Kathete} \qquad a \qquad [m] \\
\\ a =\sqrt{c^{2} - b^{2} }\\ \textbf{Gegeben:} \\ c=\frac{1}{2}m \qquad b=\frac{2}{5}m \qquad \\ \\ \textbf{Rechnung:} \\
a =\sqrt{c^{2} - b^{2} } \\
c=\frac{1}{2}m\\
b=\frac{2}{5}m\\
a =\sqrt{(\frac{1}{2}m)^{2} - (\frac{2}{5}m)^{2} }\\\\a=\frac{3}{10}m
\\\\\\ \small \begin{array}{|l|} \hline c=\\ \hline \frac{1}{2} m \\ \hline 5 dm \\ \hline 50 cm \\ \hline 500 mm \\ \hline 5\cdot 10^{5} \mu m \\ \hline \end{array} \small \begin{array}{|l|} \hline b=\\ \hline \frac{2}{5} m \\ \hline 4 dm \\ \hline 40 cm \\ \hline 400 mm \\ \hline 4\cdot 10^{5} \mu m \\ \hline \end{array} \small \begin{array}{|l|} \hline a=\\ \hline \frac{3}{10} m \\ \hline 3 dm \\ \hline 30 cm \\ \hline 300 mm \\ \hline 3\cdot 10^{5} \mu m \\ \hline \end{array}$