Question

Evaluate the following:

`sec^-1(sec  (25pi)/6)`

Answer 1

We know that

sec^-1 (sec θ) = θ,    [0, π/2) ∪ (π/2, π]

 We have 

`sec^-1(sec  (25pi)/6)=sec^-1[sec(4pi+pi/6)]`

`=sec^-1[sec(pi/6)]`

`=pi/6`