Exams › JEE Main › 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.

Related JEE Main Maths questions

• In triangle ABC, the ratio tanA: tanB: tanC = 1: 2: 1. Find the value of tanA*tanC + tanB*tanC + tanA*tanB.
• Evaluate the product sin12deg * sin48deg * sin54deg.
• Evaluate sin²(72deg) - sin²(60deg).
• Let A be the set {(n, 2n): n ∈ N} and let B be the set {(2n, 3n): n ∈ N}. What is the intersection A ∩ B?
• Let set A contain 3 elements and set B contain 6 elements. Then the cardinality of their union must satisfy
• Given the sets A = {1, 2, 5} and B = {3, 4, 5, 9}, what is A ∩ B?

⚔️ Practice JEE Main Maths free + battle 1v1 →