Question

. Which of the following is not correct

a. tan 2x = 2tanx/(1-tan^2 ⁡x )

b.sin 2x = 2tanx/(1+tan^2 ⁡x )

c. cos 2x = (1+tan^2⁡x)/(1-tan^2 ⁡x )

d. cos 2x = cos^2 ⁡x - sin^2⁡ x

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Answer 1

. Which of the following is not correct

a. tan 2x = 2tanx/(1-tan^2 ⁡x )

b.sin 2x = 2tanx/(1+tan^2 ⁡x )

c. cos 2x = (1+tan^2⁡x)/(1-tan^2 ⁡x )

d. cos 2x = cos^2 ⁡x - sin^2⁡ x

your answer is d