Exams › JEE Advanced › Maths

Is the following identity correct? sin(45deg + A) * sin(45deg - A) = (1/2) cos 2A.

1. True
2. False
3. Cannot be determined
4. None of these

Correct answer: True

Solution

Applying the product-to-difference formula gives (1/2)[cos2A - cos90deg] = (1/2)cos2A, so the identity holds.

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