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If Aa n dB are acute positive angles sat...

If `Aa n dB` are acute positive angles satisfying the equations `3sin^2A+2sin^2B=1a n d3sin2A-2sin2B=0,t h e nA+2B` is equal to `pi` (b) `pi/2` (c) `pi/4` (d) `pi/6`

A

`pi/4`

B

`pi/2`

C

`(3pi)/(4)`

D

`(2pi)/(3)`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to analyze the given equations step by step. ### Step 1: Analyze the first equation The first equation given is: \[ 3\sin^2 A + 2\sin^2 B = 1 \] Rearranging this equation gives us: \[ 3\sin^2 A = 1 - 2\sin^2 B \] ### Step 2: Use the identity for cosine We can express \( 1 - 2\sin^2 B \) using the cosine double angle identity: \[ 1 - 2\sin^2 B = \cos 2B \] Thus, we rewrite the equation as: \[ 3\sin^2 A = \cos 2B \] ### Step 3: Analyze the second equation The second equation given is: \[ 3\sin 2A - 2\sin 2B = 0 \] Rearranging this gives us: \[ 3\sin 2A = 2\sin 2B \] Dividing both sides by 2: \[ \frac{3}{2}\sin 2A = \sin 2B \] ### Step 4: Substitute \( \sin 2B \) From the previous step, we have: \[ \sin 2B = \frac{3}{2}\sin 2A \] ### Step 5: Substitute \( \sin 2B \) into the cosine equation Using the identity \( \sin 2B = 2\sin B \cos B \), we can express \( \sin 2B \) in terms of \( A \): \[ 2\sin B \cos B = \frac{3}{2}(2\sin A \cos A) \] This simplifies to: \[ 2\sin B \cos B = 3\sin A \cos A \] ### Step 6: Solve for \( A + 2B \) From the rearranged equations, we can derive a relationship between \( A \) and \( B \). We know that: \[ \cos 2B = 3\sin^2 A \] And from the second equation, we can derive: \[ \sin 2B = 3\sin A \cos A \] Using the cosine and sine relationships, we can find that: \[ A + 2B = \frac{\pi}{2} \] ### Conclusion Thus, the value of \( A + 2B \) is: \[ \boxed{\frac{\pi}{2}} \]
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ARIHANT MATHS ENGLISH-TRIGONOMETRIC FUNCTIONS AND IDENTITIES-Exercise (Questions Asked In Previous 13 Years Exam)
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  8. If sin^ 4 x/2+cos^4 x/3 =1/5 then

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