SOLUTION: Find the reference number of t = 11π/7 and t = 11π/5? t = 11π/7 t = 11π/5 the reference number is the shortest arc length from Pt to the x-axis. pl

 is positive so it's the red counter-clockwise arc
around the unit circle from (1,0).  The red arc extends 
from (1,0) to (-1,0) and since it's ,
it's  of that arc more, which is a tad more as the red arc we
see below.  Then the green arc is the reference number.



Since it's  units all the way around the unit circle and the
red arc is , the green arc is  

Answer:  is the reference number.

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 is positive and therefore it goes counter-clockwise.
It's also more than , so it's more than 1 complete revolution. In 
fact it goes all the way around the unit circle and overlaps  of the way 
past (1,0) toward (-1,0). 
It's the red counter-clockwise arc below that goes around the unit circle from
(1,0) past (-1,0) on around back to (1,0) and overlaps  of the way 
past where it started at (1,0). Then the green arc is the reference number.
It's the arc that equals the amount which the red arc goes past 1 revolution
or  



Since it's  units all the way around the unit circle and the
red arc is , the green arc is  

Answer:  is the reference number.

Edwin