Skip to main contentSkip to solution

The principal value of cot⁡−1(−13)\cot^{-1}\left(-\frac{1}{\sqrt{3}}\right)

Solution

✅ Correct Option: 4

Range of cot⁡−1\cot^{-1} is (0,π)(0, \pi). We need angle in this range with cot⁡θ=−1/3\cot\theta = -1/\sqrt{3}. Now cot⁡(2π/3)=cos⁡(2π/3)/sin⁡(2π/3)=(−1/2)/(3/2)=−1/3\cot(2\pi/3) = \cos(2\pi/3)/\sin(2\pi/3) = (-1/2)/(\sqrt{3}/2) = -1/\sqrt{3}. So cot⁡−1(−1/3)=2π/3\cot^{-1}(-1/\sqrt{3}) = 2\pi/3.

Keyboard Shortcuts

  • Left arrow: Previous question
  • Right arrow: Next question
  • S key: Jump to solution
  • Q key: Jump to question