TS EAMCET · Maths · Trigonometric Ratios & Identities
\(\cos A=\frac{3}{4} \Rightarrow 32 \sin \left(\frac{A}{2}\right) \sin \left(\frac{5 A}{2}\right)=\)
- A 7
- B 8
- C 13
- D 11
Answer & Solution
Correct Answer
(D) 11
Step-by-step Solution
Detailed explanation
\begin{aligned} & 16\left[2 \sin \frac{A}{2} \sin \left(\frac{5 A}{2}\right)\right]=16[\cos 2 A-\cos 3 A] \\ & =16\left[2 \cos ^2 A-1-\left(4 \cos ^3 A-3 \cos A\right)\right] \\ & =16\left[2\left(\frac{3}{4}\right)^2-1-\left(4 \times \frac{27}{64}-3 \times…
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