Question 1138364
{{{drawing(300,300,-1.1,1.1,-1.1,1.1,
grid(0),arrow(0,0,-1.04,0.6),
red(arc(0,0,0.6,0.6,-150,0)),
locate(0.2,0.4,red(5pi/6)),
red(triangle(-0.25,0.15,-0.25,0.25,-0.15,0.15)),
green(arc(0,0,1,1,-180,-150)),locate(-0.6,0.3,green(pi/6)),
blue(arc(0,0,1.6,1.6,0,210)),
blue(triangle(-0.67,0.4,-0.74,0.4,-0.67,0.33)),
locate(0.05,-0.5,blue(-7pi/6))
)}}} A full clockwise turn is {{{2pi}}} , half a clockwise turn is {{{pi}}} ,
and {{{5pi/6}}} is a smaller clockwise turn than {{{pi}}}.
Those are all positive angles because the are clockwise turns.
If we add one clockwise turn to {{{5pi/6}}} we get
{{{2pi+5pi/6=(2+5/6)pi=(17/5)pi=highlight(17pi/5)}}} ,
which is a positive angle coterminal with {{{5pi/6}}} .

{{{5pi/6}}} is {{{pi-5pi/6=pi/6}}} short of {{{pi}}} .
Half a clockwise turn is {{{-pi}}} ,
if we add a clockwise angle of {{{-pi/6}}} to {{{-pi}}}, we get
{{{-pi-pi/6=(-1-1/6)pi=(-7/6)pi=highlight(-7pi/6)}}} , a negative angle coterminal with {{{5pi/6}}} .