Bestimme das Maß des Winkels α im Dreieck ABC.

Die Summe der innenwinkel im Dreieck beträgt ${180}^{\circ }180^\backslash circ$.

Der Winkel $\mathrm{\angle }ABC={180}^{\circ }-{90}^{\circ }-{55}^{\circ }={35}^{\circ }\backslash angle\; ABC=180^\backslash circ-90^\backslash circ-55^\backslash circ=35^\backslash circ$

$\alpha ={180}^{\circ }-\mathrm{\angle }ABC-{90}^{\circ }={55}^{\circ }\backslash alpha=180^\backslash circ-\backslash angle\; ABC-90^\backslash circ=55^\backslash circ$

Das Maß des Winkels $\alpha ={55}^{\circ }\backslash alpha=55^\backslash circ$.