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pottersheep

  • 3 years ago

Trig Identities....Half Angles help PLEASEEEEE!!! Can someone explain what the teacher wrote on the board for me please??? Cos2A = cos^2A-sin^2A = 1 - 2sin^2 A (What happened here???????)

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  1. Rezz5
    • 3 years ago
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    sin^2 + cos^2 =1

  2. Rezz5
    • 3 years ago
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    1-cos^2==sin^2

  3. Rezz5
    • 3 years ago
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    sub in ... Cos2A=cos^2A-1+cos^2A

  4. Rezz5
    • 3 years ago
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    Cos2A=2cos^2A -1

  5. Rezz5
    • 3 years ago
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    now do same thing with 1-sin^2= cos^2 and you should get the identity you teacher wrote sooooo 1-sin^2=cos^2 sub into Cos2A = cos^2A-sin^2A Cos2A=1-sin^2A-sin^A ==1-2sin^2A

  6. pottersheep
    • 3 years ago
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    HMmm let me process what you said

  7. pottersheep
    • 3 years ago
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    Thank you! I finally get it!

  8. Rezz5
    • 3 years ago
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    yw

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