Q. 21

# Mark the Correct alternative in the following:

is equal to

A.cos x

B. sin x

C. - cos x

D. sin x

Answer :

Given expression

[Using the formulae sin3x = 3sinx – 4sin^{3}x and cos2x = 1 – 2sin^{2}x]

= sin x

Hence the answer is option B.

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