The general value of $x$ for which $\cos \,\,2x,\,\,\frac{1}{2}\;\,\,{\rm{and}}\,\,\sin \,\,2x$ are in AP, are given by

$n\pi ,\;\,n\pi + \frac{\pi }{2}$

$n\pi + \frac{\pi }{4},\,\;\frac{{3n\pi }}{4}$

JEE MATHEMATICS MCQ: TRIGONOMETRIC EQUATIONS

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Application +4 | -1

The general value of

x

for which

\cos \,\,2x,\,\,\frac{1}{2}\;\,\,\mathrm{and}\,\,\sin \,\,2x

are in AP, are given by

View answer and explanation

Correct option: B

n\pi ,\;\,n\pi + \frac{\pi }{4}

Option B (-1) is correct because the sum telescopes to

\cos \pi

which equals -1.

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