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Prove that: sin2 24° – sin2 6° = (√5 – 1)/8 |
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Answer» Let us consider the LHS sin2 24° – sin2 6° As we know, sin (A + B) sin (A – B) = sin2A – sin2B Now the above equation becomes, sin2 24° – sin2 6° = sin (24° + 6°) – sin (24° – 6°) = sin 30° – sin 18° = sin 30° – (√5 – 1)/4 [since, sin 18° = (√5 – 1)/4] = 1/2 × (√5 – 1)/4 = (√5 – 1)/8 = RHS Thus proved. |
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