The value of (2 ^-1(-7)) is: - Mathematics MCQ Mathematics Mock Test - 5 2026 | ExamTest.live

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The value of cos (2 tan^{- 1} (- 7)) is:

Solution & Step-by-step Explanation

Let tan^{- 1} (- 7) = θ ⟹ tan θ = - 7 .We need to find cos (2 θ) .Using the identity cos 2 θ = \frac{1 - t a n ^{2} θ}{1 + t a n ^{2} θ} : cos 2 θ = \frac{1 - ( - 7 ) ^{2}}{1 + ( - 7 ) ^{2}} cos 2 θ = \frac{1 - 49}{1 + 49} = \frac{- 48}{50} cos 2 θ = - \frac{24}{25}

Try it yourself before checking the explanation above.

The value of cos (2 tan^{- 1} (- 7)) is:

49/50

- 49/50

24/25

- 24/25

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