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Statement-1: cos((pi)/(10))cos((2pi)/(10...

Statement-1: `cos((pi)/(10))cos((2pi)/(10))cos((4pi)/(10))=(cos((8pi)/(10)))/(2^(3)sin((pi)/(10)))`
Statement-2: `cos A.cos2A.cos2^(2)A.......cos(2^(n-1)A)=(sin(2^(n)A))/(2^(n)sinA)`

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To solve the problem, we need to analyze both statements and determine their validity step by step. ### Statement 1: We need to verify the equation: \[ \cos\left(\frac{\pi}{10}\right) \cos\left(\frac{2\pi}{10}\right) \cos\left(\frac{4\pi}{10}\right) = \frac{\cos\left(\frac{8\pi}{10}\right)}{2^3 \sin\left(\frac{\pi}{10}\right)} \] **Step 1: Rewrite the Left-Hand Side (LHS)** Start with the left-hand side: \[ \cos\left(\frac{\pi}{10}\right) \cos\left(\frac{2\pi}{10}\right) \cos\left(\frac{4\pi}{10}\right) \] **Hint:** Use the identity \( \sin(2a) = 2 \sin(a) \cos(a) \). **Step 2: Apply the Identity** We can multiply and divide by \( 2 \sin\left(\frac{\pi}{10}\right) \): \[ = \frac{2 \sin\left(\frac{\pi}{10}\right) \cos\left(\frac{\pi}{10}\right) \cos\left(\frac{2\pi}{10}\right) \cos\left(\frac{4\pi}{10}\right)}{2 \sin\left(\frac{\pi}{10}\right)} \] The numerator becomes: \[ = \frac{\sin\left(\frac{2\pi}{10}\right) \cos\left(\frac{2\pi}{10}\right) \cos\left(\frac{4\pi}{10}\right)}{2 \sin\left(\frac{\pi}{10}\right)} \] **Hint:** Recognize that \( \sin(2a) = 2 \sin(a) \cos(a) \). **Step 3: Simplify Further** Now, we can apply the identity again: \[ = \frac{\sin\left(\frac{2\pi}{10}\right) \cdot \frac{1}{2} \sin\left(\frac{4\pi}{10}\right)}{2 \sin\left(\frac{\pi}{10}\right)} \] Continuing this process leads to: \[ = \frac{\sin\left(\frac{8\pi}{10}\right)}{2^3 \sin\left(\frac{\pi}{10}\right)} \] **Step 4: Compare Both Sides** Now we have: \[ \cos\left(\frac{\pi}{10}\right) \cos\left(\frac{2\pi}{10}\right) \cos\left(\frac{4\pi}{10}\right) = \frac{\sin\left(\frac{8\pi}{10}\right)}{2^3 \sin\left(\frac{\pi}{10}\right)} \] Since \( \sin\left(\frac{8\pi}{10}\right) = \cos\left(\frac{8\pi}{10}\right) \), we find that the statement is indeed true. ### Statement 2: We need to verify the equation: \[ \cos A \cos(2A) \cos(2^2 A) \ldots \cos(2^{n-1} A) = \frac{\sin(2^n A)}{2^n \sin A} \] **Step 1: Rewrite the Left-Hand Side (LHS)** Start with the left-hand side: \[ \cos A \cos(2A) \cos(2^2 A) \ldots \cos(2^{n-1} A) \] **Hint:** Again, use the identity \( \sin(2a) = 2 \sin(a) \cos(a) \). **Step 2: Apply the Identity** Multiply and divide by \( 2 \sin A \): \[ = \frac{2 \sin A \cos A \cos(2A) \ldots \cos(2^{n-1} A)}{2 \sin A} \] The numerator becomes: \[ = \frac{\sin(2A) \cos(2A) \ldots \cos(2^{n-1} A)}{2 \sin A} \] **Step 3: Continue Simplifying** Continuing this process leads to: \[ = \frac{\sin(2^n A)}{2^n \sin A} \] **Step 4: Compare Both Sides** Now we have: \[ \cos A \cos(2A) \cos(2^2 A) \ldots \cos(2^{n-1} A) = \frac{\sin(2^n A)}{2^n \sin A} \] This statement is also true. ### Conclusion: - **Statement 1** is true. - **Statement 2** is true. ### Final Answer: Both statements are correct.
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