$$ \begin{aligned} & \mathrm{L}_1: x-y=0 \\ & \mathrm{~L}_2: x+2 y=3 \\ & \mathrm{~L}_3: x+y=6 \end{aligned} $$ on solving $\mathrm{L}_1$ and $\mathrm{L}_2$ : $y=L$ and $x=1$ $\mathrm{L}_1$ and $\mathrm{L}_3$ : $$ \begin{aligned} & x=2 \\ & y=2 \end{aligned} $$ $\mathrm{L}_2$ and $\mathrm{L}_{3 \text { ain }}$. $$ \begin{aligned} & x+y=3 \\ & 2 x+y=6 \\ & x=3 \\ & y=0 \\ & A C=\sqrt{4+1}=\sqrt{5} \\ & B C=\sqrt{4+1}=\sqrt{5} \\ & A B=\sqrt{1+1}=\sqrt{2} \end{aligned} $$ sa its an isosceles triangle