\begin{tikzpicture}
            \tkzDefPoint(0,0){0}
            \tkzDefPoint(2,0){A}
            \tkzDefPoint(30:1.5){z}
            \tkzDefPoint(30:-2.667){za}
            \draw[dashed] (30:-3)--(30:2.7) node[right]{(1)};
            \draw[dashed] (120:-2.7)--(120:2.7) node[right]{(2)};
            \tkzDefLine[perpendicular=through 0, K=.-1](za,z)
            \tkzGetPoint{c}
            \tkzInterLC(0,c)(0,A)\tkzGetPoints{T1}{T}
            \tkzDrawCircle[solid,color=brown](0,A)
            \tkzDrawPoints[size=8,fill=red](0,z,za,T)
            \tkzLabelPoints(z,T)
            \tkzLabelPoints[below](0)
            \draw[dashed](z)--(T) node[midway, right]{(3)};
            \draw[dashed](T)--(za) node[midway, above]{(4)};
            \tkzMarkRightAngle(z,T,za)
            \tkzMarkRightAngle(z,0,T)
            \draw (za) node[below]{$z_a$};
            \pgfresetboundingbox
            \draw (-2,-2) (2,2);
            \end{tikzpicture}