1. The secant is defined as the inverse function of co-secant or cos function
Hence when the cosine is 0, the secant is 1/0 which is undefined. So, when cosine is 0, secant is undefined
Cos 30 =

Cos 45 =

Cos 180 = -1
cos 270 =0
Since cos 270 is 0, secant of 270 is undefined
Answer is d: 270
2. cosec (-x) = - cosec (180 -x)
We have cosec(-166) = - cosec (180-14) = -cosec (14)
Alternatively we can confirm this as csc (-166) = -4.133565 and -csc(14) = -4.133565; Hence, we can reconfirm that the answer arrived at is right
Therefore csc (-166) = -csc(14) (Option B) is the right answer