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jkl3inberg Group Title

Use a sum or difference formula to find the exact value of the following: sin(5π/7)cos(π/21)-cos(5π/7)sin(π/21)

  • one year ago
  • one year ago

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  1. cwrw238 Group Title
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    use the identity sin (a - b) = sin a cos b - cos a sin b

    • one year ago
  2. jdoe0001 Group Title
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    http://www.mathplanet.com/images/math/codecogs_ca939b37.gif

    • one year ago
  3. cwrw238 Group Title
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    so your expression becomes sin (5pi/7 + pi/21)

    • one year ago
  4. cwrw238 Group Title
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    = sin 16pi/21

    • one year ago
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