If n is an integer,n•180° represents an integer multiple of 180° and
(2n+1)•90° represents an odd integer multiple of
90°,and so on. Determine whether the expression is equal to 0,
1,−1, or is undefined.
csc(n•180°)=
csc ( n * 180) = 1 / sin (n * 180) but sin 180 = 0 so sin (n*180) = 0
So
1 / 0 = undefined
+84 
