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Solve the equation , sqrt(3) sin 2A = s...

Solve the equation , ` sqrt(3) sin 2A = sin 2B and sqrt(3)sin^(2)A + sin^(2)B=(1)/(2)(sqrt(3)-1)`.

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To solve the equations \( \sqrt{3} \sin 2A = \sin 2B \) and \( \sqrt{3} \sin^2 A + \sin^2 B = \frac{1}{2}(\sqrt{3}-1) \), we will follow these steps: ### Step 1: Rewrite the first equation We start with the first equation: \[ \sqrt{3} \sin 2A = \sin 2B \] This can be rearranged to: \[ \sqrt{3} \sin 2A - \sin 2B = 0 \] Let’s denote this as Equation (1). ### Step 2: Rewrite the second equation Next, we look at the second equation: \[ \sqrt{3} \sin^2 A + \sin^2 B = \frac{1}{2}(\sqrt{3}-1) \] We can denote this as Equation (2). ### Step 3: Use double angle identities Using the double angle identity, we know: \[ \sin^2 A = \frac{1 - \cos 2A}{2} \quad \text{and} \quad \sin^2 B = \frac{1 - \cos 2B}{2} \] Substituting these into Equation (2): \[ \sqrt{3} \left(\frac{1 - \cos 2A}{2}\right) + \left(\frac{1 - \cos 2B}{2}\right) = \frac{1}{2}(\sqrt{3}-1) \] Multiplying through by 2 to eliminate the fractions: \[ \sqrt{3}(1 - \cos 2A) + (1 - \cos 2B) = \sqrt{3} - 1 \] This simplifies to: \[ \sqrt{3} - \sqrt{3} \cos 2A + 1 - \cos 2B = \sqrt{3} - 1 \] Rearranging gives: \[ -\sqrt{3} \cos 2A - \cos 2B = -2 \] Multiplying through by -1: \[ \sqrt{3} \cos 2A + \cos 2B = 2 \] Let’s denote this as Equation (3). ### Step 4: Square both equations Now we have: 1. \( \sqrt{3} \sin 2A - \sin 2B = 0 \) (Equation 1) 2. \( \sqrt{3} \cos 2A + \cos 2B = 2 \) (Equation 3) Next, we square both equations: From Equation (1): \[ 3 \sin^2 2A - 2\sqrt{3} \sin 2A \sin 2B + \sin^2 2B = 0 \] From Equation (3): \[ 3 \cos^2 2A + 2\sqrt{3} \cos 2A \cos 2B + \cos^2 2B = 4 \] ### Step 5: Combine the equations Now we can add these two equations together. The sine and cosine identities will help us simplify: Using \( \sin^2 \theta + \cos^2 \theta = 1 \): \[ 3(\sin^2 2A + \cos^2 2A) + (\sin^2 2B + \cos^2 2B) = 4 + 2\sqrt{3} \cos 2A \cos 2B \] This simplifies to: \[ 3 + 1 = 4 + 2\sqrt{3} \cos 2A \cos 2B \] Thus we get: \[ 4 = 4 + 2\sqrt{3} \cos 2A \cos 2B \] This implies: \[ 2\sqrt{3} \cos 2A \cos 2B = 0 \] Thus, either \( \cos 2A = 0 \) or \( \cos 2B = 0 \). ### Step 6: Solve for \( A \) and \( B \) 1. If \( \cos 2A = 0 \): \[ 2A = \frac{\pi}{2} + n\pi \implies A = \frac{\pi}{4} + \frac{n\pi}{2}, \quad n \in \mathbb{Z} \] 2. If \( \cos 2B = 0 \): \[ 2B = \frac{\pi}{2} + m\pi \implies B = \frac{\pi}{4} + \frac{m\pi}{2}, \quad m \in \mathbb{Z} \] ### Final Result Thus, the general solutions for \( A \) and \( B \) are: \[ A = \frac{\pi}{4} + \frac{n\pi}{2}, \quad B = \frac{\pi}{4} + \frac{m\pi}{2}, \quad n, m \in \mathbb{Z} \]
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