1)

 The principal solutions  of  cotx=3 are


A) π6,7π6

B) π3,7π3

C) π4,5π4

D) π6,5π6

Answer:

Option A

Explanation:

 we have,

  cotx=3 

   cotx=cotπ6 or   cot(π+π6)

    x=π6,7π6

  principal solution is   π6,7π6