$\begin{array}{l} \text{Gegeben:}\\\text{Winkel} \qquad \alpha \qquad [^{\circ}] \\ \text{Länge der Seite} \qquad c \qquad [m] \\ \text{Länge der Seite} \qquad b \qquad [m] \\ \\ \text{Gesucht:} \\\text{Länge der Seite} \qquad a \qquad [m] \\ \\ a = \sqrt{b^{2} +c^{2} -2\cdot b\cdot c\cdot cos\alpha }\\ \textbf{Gegeben:} \\ \alpha=80^{\circ} \qquad c=\frac{1}{2}m \qquad b=\frac{3}{4}m \qquad \\ \\ \textbf{Rechnung:} \\ a = \sqrt{b^{2} +c^{2} -2\cdot b\cdot c\cdot cos\alpha } \\ \alpha=80^{\circ}\\ c=\frac{1}{2}m\\ b=\frac{3}{4}m\\ a = \sqrt{(\frac{3}{4}m)^{2} +(\frac{1}{2}m)^{2} -2\cdot \frac{3}{4}m \cdot \frac{1}{2}m\cdot cos80^{\circ} }\\\\a=0,826m \\\\\\ \small \begin{array}{|l|} \hline alpha=\\ \hline 80 ° \\ \hline 4,8\cdot 10^{3} \text{'} \\ \hline 2,88\cdot 10^{5} \text{''} \\ \hline 88\frac{8}{9} gon \\ \hline 1,4 rad \\ \hline \end{array} \small \begin{array}{|l|} \hline c=\\ \hline \frac{1}{2} m \\ \hline 5 dm \\ \hline 50 cm \\ \hline 500 mm \\ \hline 5\cdot 10^{5} \mu m \\ \hline \end{array} \small \begin{array}{|l|} \hline b=\\ \hline \frac{3}{4} m \\ \hline 7\frac{1}{2} dm \\ \hline 75 cm \\ \hline 750 mm \\ \hline 7,5\cdot 10^{5} \mu m \\ \hline \end{array} \small \begin{array}{|l|} \hline a=\\ \hline 0,826 m \\ \hline 8,26 dm \\ \hline 82,6 cm \\ \hline 826 mm \\ \hline 8,26\cdot 10^{5} \mu m \\ \hline \end{array} \end{array}$