Complete the Sentence So the Result Is an Identity $\cot \frac { 17 \pi } { 18 }$

Multiple Choice

Complete the sentence so the result is an identity. Let x be any real number.
- $\cot \frac { 17 \pi } { 18 }$

A) $\tan \frac { \pi } { 18 }$
B) $\cot \frac { \pi } { 18 }$
C) $\cot \frac { - 4 \pi } { 9 }$
D) $\tan \frac { - 4 \pi } { 9 }$