\begin{tikzpicture}
                \clip(0,0) circle (2cm);
                \tkzDefPoint(0,0){o}
                \tkzDefPoint(2,0){a}
                \tkzDefPoint(240:1.6){p}
                \tkzDefPoint(130:.8){u}
                \tkzDefPoint(20:1.4){v}
                \tkzDrawCircle[dashed, color=blue](o,a)
                \hypsegment{p}{u}{o}{a}
                \hypsegment{v}{p}{o}{a}
                \hypsegment{u}{v}{o}{a}
                \tkzDrawPoints[fill=red](p,u,v)
                \draw (130:.44) node{$\gamma$};
                \draw (240:1) node {$\beta$};
                \draw (20:.8) node {$\alpha$};
                \draw (-.6,-.2) node{$a$};
                \draw (.3,.7) node{$b$}; 
                \draw (.2,-.6) node{$c$};
\end{tikzpicture}