JEE MATHEMATICS MCQ: MULTIPLE AND SUBMULTIPLE ANGLES

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Application +4 | -1

\sin \beta

is the geometric mean between

\sin \alpha

and

\cos \alpha

, then

\cos 2 \beta

is equal to

View answer and explanation

Correct option: A

2 \sin ^2\left(\frac{\pi}{4}-\alpha\right)

Option A (

2 \sin ^2\left(\frac{{\pi}}{{4}}-\alpha\right)

) is correct because by using the given geometric mean condition and trigonometric identities, we can express

\cos 2\beta

in terms of

\alpha

and simplify it to the given form.

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