To find: Value of

We have,

[∵ sec(-θ) = sec θ]

Putting π = 180°

= sec[25 × 60°]

= sec[1500°]

= sec [90° × 16 + 60°]

Clearly, 1500° is in I^st Quadrant and the multiple of 90° is even

= sec 60°

= 2