The principal value of sec⁻¹(−2) is:

The principal value of sec⁻¹(−2) is:

• A. π/3
• B. 2π/3
• C. −π/3
• D. π/6

Answer: B) 2π/3

Explanation: sec⁻¹(−2) = π − sec⁻¹(2) = π − π/3 = 2π/3, which lies in [0, π] − {π/2}, the principal branch of sec⁻¹.