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	\begin{center}
	\begin{tikzpicture}
		\draw [line width=0.5pt,->] (3,3)--(1.5,3);
		\draw [line width=0.5pt,->] (1.5,3)--(0,3);
		\draw [line width=0.5pt,->] (90:3)arc(90:180:3);
		\draw [line width=0.5pt,->] (0,3)--(-1.5,3) node [left] {$x_{g}$};
		\draw [line width=0.5pt,->] (0,0)--(90:4) node [left] {$y_{g}$};
		\draw [line width=0.5pt,->] (0,0)--(140:4) node [left] {$y_{f}$};
	\end{tikzpicture}
	\end{center}