Question

For the principal value, evaluate the following:

`cosec^-1(2tan  (11pi)/6)`

Answer 1

`cosec^-1(2tan  (11pi)/6)=cosec^-1[2xx(-1/sqrt3)]`

`=cosec^-1[-2/sqrt3]`

`=cosec^-1[cosec(-pi/3)]`

`=-pi/3`