secx=2

⇒ cos x = 1/2

cos x = cos π/3

Using formula for general soluton of cos x = cos y i.e x = 2n π y

We have x = 2n π - π/ 3

The solutions that lie in the interval 0 to 2 π , both included are principal solution

So they are , in this case ,

π/3, 2 π- π/ 3 = 5π/ 3