JEE MATHEMATICS MCQ: TRIGONOMETRY RATIOS

1 Easy

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Consider the statements given below:

I.

2 \cos x \cdot \cos y=\cos (x+y)-\cos (x-y)

.

II.

-2 \sin x \cdot \sin y=\cos (x+y)-\cos (x-y)

.

III.

2 \sin x \cdot \cos y=\sin (x+y)-\sin (x-y)

.

IV.

2 \cos x \cdot \sin y=\sin (x+y)+\sin (x-y)

.

Choose the correct statements.

View answer and explanation

Correct option: B

II is correct

Option B is correct because the identity

-2 \sin x \cdot \sin y = \cos(x+y) - \cos(x-y)

is a standard trigonometric identity.

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