The cotangent function is defined as the ratio between cosine and sine of a given angle, i.e.

Since you can't have zero at the denominator, the cotangent function is not defined when the sine is zero.
Let's look at your option:
, so the cotangent is defined here
, so the cotangent is not defined here
, so the cotangent is defined here
, so the cotangent is defined here
What two cars, I don’t see anything
3×2=692047 82837=284749×2484r133.e9274
C=2πr=2·π·13≈81.68141
C=81.68