I am having trouble trying to understand the hexagonal boundary in $t_3$ and $y$ representation of $SU (3)$. I tried to work it out like we did in $SU \left( 2 \right)$ but got not luck. Could someone please explain the routine of understanding this? I appreciate that.
By the way, I did not post my work because it did not work, I can post my work if people are curious.