What is the critical depth for a grassy triangular channel with $2$H:$1$V side slopes and a $0\mathrm{.}5\%$ slope when the flow is $3\mathrm{.}00$ m$3/$s$?$ If the channel is actually flowing at a depth of $1\mathrm{.}2$ m$,$ is the flow critical, subcritical, or supercritical? $[9$ marks$]$

Given Q$2=[$gAc$3/$Bs$]$