Let $0 < alpha < 2$ and let $T_alpha ( heta) = alpha tan( heta/2)$. $T_alpha$ has an attractive fixed point at $ heta = 0$. We denote by $C(alpha)$ the set of points in $I = [-pi, pi]$ which are not attracted to $ heta = 0$ by the succesive iterations of $T_alpha$. That is, $C(alpha)$ is the set of points in I where the dynamics of $T_alpha$ is chaotic.