The value of $\tan^{-1}(1) + \tan^{-1}(2) + \tan^{-1}(3)$ is:
Step-by-Step Solution
Key Concept: Combine $\tan^{-1}(2) + \tan^{-1}(3)$ first. Since $2 \cdot 3 > 1$ and both are positive, the addition formula gives a result $> \pi/2$. Add the correction $+\pi$.
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Correct Answer: (2)