Question:
If 3 tan-1 x + cot-1 x = π, then x equals
(a) 0
(b) 1
(c) -1
(d) ½
Solution:
(b) 1
Given, 3 tan-1 x + cot-1 x = π
2 tan-1 x + tan-1 x + cot-1 x = π
2 tan-1 x + π/2 = π (As tan-1 + cot-1 = π/2)
2 tan-1 x = π/2
tan-1 x = π/4
x = 1
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