Beispiel Nr: 01
$\text{Gegeben:}\\\text{Kreiszahl} \qquad \pi \qquad [] \\ \text{Radius (außerer Kreis)} \qquad r_{a} \qquad [m] \\ \text{Radius (innerer Kreis)} \qquad r_{i} \qquad [m] \\ \\ \text{Gesucht:} \\\text{Fläche} \qquad A \qquad [m^{2}] \\ \\ A = (r_{a} ^{2} - r_{i} ^{2} )\cdot\pi\\ \textbf{Gegeben:} \\ \pi=3,14 \qquad r_{a}=4m \qquad r_{i}=6m \qquad \\ \\ \textbf{Rechnung:} \\ A = (r_{a} ^{2} - r_{i} ^{2} )\cdot \pi \\ \pi=3,14\\ r_{a}=4m\\ r_{i}=6m\\ A = (4m ^{2} - 6m ^{2} )\cdot 3,14\\\\A=-62,8m^{2} \\\\ \tiny \begin{array}{|l|} \hline ra=\\ \hline 4 m \\ \hline 40 dm \\ \hline 400 cm \\ \hline 4\cdot 10^{3} mm \\ \hline 4\cdot 10^{6} \mu m \\ \hline 0,004 km \\ \hline \end{array} \tiny \begin{array}{|l|} \hline ri=\\ \hline 6 m \\ \hline 60 dm \\ \hline 600 cm \\ \hline 6\cdot 10^{3} mm \\ \hline 6\cdot 10^{6} \mu m \\ \hline 0,006 km \\ \hline \end{array} \tiny \begin{array}{|l|} \hline A=\\ \hline -62,8 m^2 \\ \hline -6,28\cdot 10^{3} dm^2 \\ \hline -6,28\cdot 10^{5} cm^2 \\ \hline -6,28\cdot 10^{7} mm^2 \\ \hline -0,628 a \\ \hline -0,00628 ha \\ \hline -6,28\cdot 10^{-5} km^2 \\ \hline \end{array}$