Question 9
Three parallel lines $L_1$, $L_2$ and $L_3$ are such that $L_1$ is 1 cm above $L_2$ and $L_3$ is 2 cm below $L_2$. A right isosceles triangle has one of its vertices on each line. What is the sum, in $\mathrm{cm}^2$, of all possible values for the area of this triangle?