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MathsHardMCQ2019 · 10 Jan Shift 2

Q77.The value of cot(∑19n=1 cot−1(1 + ∑np=1 2p)) is: (1) 21 (2) 19 19 21 (3) 2223 (4) 2223

What This Question Tests

This problem requires simplifying a complex summation involving inverse cotangent functions by recognizing it as a telescopic series using the property of tan⁻¹(x) - tan⁻¹(y).

Concepts Tested

Inverse tangent identitiesTelescopic seriesSummation techniques

Formulas Used

cot^-1(x) = tan^-1(1/x)

tan^-1(x) - tan^-1(y) = tan^-1((x-y)/(1+xy))

Sum of arithmetic progression

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