[Analysis] Add some notes

semester2/analysis-i/cheat-sheet-jh/parts/fields.tex

@@ -102,6 +102,8 @@ $\overline{a + bi} := a-bi$ (\tr{complex conjugate}{Komplexe Konjugation});
 Transformation polar $\rightarrow$ normal: $r \cdot \cos(\phi) + r \cdot \sin(\phi)i$.
 Transformation normal $\rightarrow$ polar: $|z| \cdot e^{i \cdot \arcsin(\frac{b}{|z|})}$;
 
+\textbf{\tr{Square root of negative number}{Quadratwurzel einer negativen Zahl}}: $\sqrt{-c} = ci$
+
 
 \begin{theorem}[]{\tr{Fundamental Theorem of Algebra}{Fundamentalsatz der Algebra}}
     \trLet $n \geq 1, n \in \N$ \tr{and let}{und sei}