Cosecant (csc) is defined as the reciprocal of sine, therefore:
[tex]y = cscx \\
y = \frac{1}{sinx} [/tex].
1/sinx will be undefined when the denominator sinx = 0.
Recalling the unit circle, sinx = 0 at x = 0 ± πn, where n is an integer.
Since the domain x is restricted from (0, 2π), we only consider the values x = 0, x = π, and x = 2π.
Therefore in the domain 0 ≤ x ≤ 2π, y = csc(x) will be undefined at x = 0, x = π, and x = 2π.
