Show that the Cross Ratio depends on $\lambda$.

Question

I am trying to prove that the cross-ratio of the lines over a field $K$ defined by $\left(\begin{array}{c} 1 \\ 0\end{array}\right), \left(\begin{array}{c} 0 \\ 1\end{array}\right), \left(\begin{array}{c} 1 \\ 1\end{array}\right), \left(\begin{array}{c} \lambda \\ 1\end{array}\right)$ is dependent of $\lambda\in K$ as a way to show that there is infinitely many quadruplets of lines which are not isomorphic to these 4 lines, since the cross-ratio is invariant under isomorphisms. The problem is that i don't understand how to get around to doing this.