Evaluate : $\tan^{-1}\left( -\frac{1}{\sqrt{3}} \right) + \cot^{-1}\left( \frac{1}{\sqrt{3}} \right) + \tan^{-1}\left( \sin\left( -\frac{\pi}{2} \right) \right) + \tan^{-1}\left( \tan \frac{2\pi}{3} \right)$

Year	Paper Code	Set	Position
CBSE 2026	Series 65-4	Set 1	Question 21
CBSE 2026	Series 65-4	Set 2	Question 22
CBSE 2026	Series 65-4	Set 3	Question 25

• Step 1: Stating the fundamental formula / law statement (+1 Mark)
• Step 2: Intermediate mathematical substitution or proof steps (+1 Mark)
• Step 3: Correct final value or conclusion with mandatory SI units (+1 Mark)