Find an angle between 0 and 2π that is coterminal with the given angle

(-13pi)/(3)

(15pi)/(9)

For -13pi/3, add 2pi until you get what you want. 2pi= 6pi/3
-13pi/3+18pi/3= 5pi/3

15pi/9 is between 0 and 2pi already. 2pi=18pi/9
0<15pi/9 < 18pi/9

Hoping this helps!