fixed typo in equation.

chapters/Classical_Supervised_Learning/k-Nearest_Neighbors.tex

@@ -33,7 +33,7 @@ Für die Klassifizierung erfolgt durch
 \paragraph{Cosine Distance}%
 \label{par:Cosine Distance}
 \begin{equation} \label{eq:cosine distance}
-    d(\bm x,\bm y) = 1 - \frac{\bm x^T \bm y}{||\bm c||\cdot||\bm y||}
+    d(\bm x,\bm y) = 1 - \frac{\bm x^T \bm y}{||\bm x||\cdot||\bm y||}
 \end{equation}
 
 \paragraph{Hamming Distance}%