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Convert the sums or differences into pro...

Convert the sums or differences into products:
`sin 12 A - sin 4 A`

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To convert the expression \( \sin 12A - \sin 4A \) into a product, we can use the sine difference identity. The identity states: \[ \sin C - \sin D = 2 \cos\left(\frac{C + D}{2}\right) \sin\left(\frac{C - D}{2}\right) \] ### Step-by-Step Solution: 1. **Identify C and D**: - Here, let \( C = 12A \) and \( D = 4A \). 2. **Apply the Identity**: - Substitute \( C \) and \( D \) into the identity: \[ \sin 12A - \sin 4A = 2 \cos\left(\frac{12A + 4A}{2}\right) \sin\left(\frac{12A - 4A}{2}\right) \] 3. **Calculate \( C + D \) and \( C - D \)**: - Calculate \( C + D \): \[ C + D = 12A + 4A = 16A \] - Calculate \( C - D \): \[ C - D = 12A - 4A = 8A \] 4. **Substitute Back into the Expression**: - Now substitute these results back into the equation: \[ \sin 12A - \sin 4A = 2 \cos\left(\frac{16A}{2}\right) \sin\left(\frac{8A}{2}\right) \] 5. **Simplify the Fractions**: - Simplifying the fractions gives: \[ \sin 12A - \sin 4A = 2 \cos(8A) \sin(4A) \] ### Final Answer: Thus, the expression \( \sin 12A - \sin 4A \) can be converted into the product: \[ \sin 12A - \sin 4A = 2 \cos(8A) \sin(4A) \]
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ICSE-COMPOUND AND MULTIPLE ANGLES -EXERCISE 5 (B)
  1. Convert the sums or differences into products: sin 12 A + sin 4 A

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  2. Convert the sums or differences into products: sin 37 ^(@) + sin 21 ...

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  3. Convert the sums or differences into products: sin 12 A - sin 4 A

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  4. Convert the sums or differences into products: cos 79^(@) + cos 11 ^...

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  5. Convert the sums or differences into products: cos 12 alpha + cos 8 ...

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  6. Convert the sums or differences into products: cos 25 ^(@) - cos 37^...

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  7. Convert the sums or differences into products: sin 61^(@) - cos 39^(...

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  8. Convert the sums or differences into products: sin 4x + cos 2x

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  9. Prove that: (sin A+sin B)/(cos A+cos B)=tan((A+B)/2)

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  10. (sin 75^(@) - sin 15 ^(@))/( cos 75^(@) + cos 15 ^(@)) = (1)/(sqrt3)

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  11. (sin 7x + sin 3x )/(cos 7x + cos 3x ) = tan 5x.

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  12. (cos 2B - cos 2 A)/( sin 2 A + sin 2 B) = tan (A -B).

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  13. (sin (4A - 2B) + sin (4B - 2 A))/( cos (4 A - 2 B) + cos (4B - 2 A))= ...

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  14. (cos alpha + 2 cos 3 alpha + cos 5 alpha )/(cos 3 alpha + 2 cos 5 alph...

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  15. ( sin A + sin 3A + sin 5A + sin 7A)/(cos A + cos 3 A + cos 5 A + cos 7...

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  16. cos 20^(@) + cos 100^(@) + cos 140^(@) = 0

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  17. Prove that :sin 10^(@) + sin 20^(@) + sin 40^(@) + sin 50^(@) = sin 70...

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  18. Prove that cos 15 ^(@) - sin 15^(@) = (1)/(sqrt2)

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  19. Prove that sin 36 ^(@) + cos 36 ^(@) = sqrt2 cos 9^(@).

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  20. Prove that cos 20^(@) cos 40^(@) cos 80^(@) = (1)/(8).

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