OCF Normal flow in circular pipe

$3\mathrm{.}00$

Water is flowing with a free surface in a concrete pipe and uniform flow is achieved:

Manning's coefficient $n=0\mathrm{.}013$

Pipe laying slope: $0\mathrm{.}0012$

Flow depth $y=4\mathrm{.}1ft$

Pipe diameter $D=6\mathrm{.}5ft$

Determine the discharge Q $.$

$1.)$ Find the angle $$ :

This angle also be converted to radians as:

$2.)$ Geometry of the channel section:

Crosssectional area $A=$

Hydraulic radius $R_h=$

$3.)$ Discharge $Q=$