JEE Mains · Maths · STD 11 - 3. trignometrical ratios,functions and identities
The value of \(36(4 \cos ^2 9^{\circ}-1)(4 \cos ^2 27^{\circ}-1) (4\cos ^2 81^{\circ}-1) (4 \cos ^2 243^{\circ}-1)\) is
- A \(54\)
- B \(18\)
- C \(27\)
- D \(36\)
Answer & Solution
Correct Answer
(D) \(36\)
Step-by-step Solution
Detailed explanation
\(4 \cos ^2 \theta-1=4\left(1-\sin ^2 \theta\right)-1=3-4 \sin ^2 \theta=\frac{\sin 3 \theta}{\sin \theta}\) so given expression can be written as…
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