JEE MATHEMATICS MCQ: TRIGONOMETRIC EQUATIONS

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Application +4 | -1

Let

I(n)=2 \cos n x, \forall \, n \in N

, then

I(1) \cdot I(n+1)-I(n)

is equal to

View answer and explanation

Correct option: B

I(n+2)

Option B (

I(n+2)

) is correct because by using the trigonometric identity

2 \cos a \cos b = \cos(a+b) + \cos(a-b)

, the expression simplifies to

I(n+2)

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