Q.If \(tanα + cotα = 2\), then the value of \(tan^{13}α + cot^{13}α\) is—? (a) 13 (b) 2 (c) 1 (d) 0
Answer: B
\(tan\alpha + cot\alpha = 2\)
or, \(tan\alpha + \cfrac{1}{tan\alpha} = 2\)
or, \(\cfrac{tan^2\alpha + 1}{tan\alpha} = 2\)
or, \(tan^2\alpha + 1 = 2tan\alpha\)
or, \(tan^2\alpha + 1 - 2tan\alpha = 0\)
or, \((tan\alpha - 1)^2 = 0\)
or, \(tan\alpha - 1 = 0\)
or, \(tan\alpha = 1\)
\(\therefore cot\alpha = 1\)

\(\therefore tan^{13}\alpha + cot^{13}\alpha = 1^{13} + 1^{13} = 1 + 1 = 2\)
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