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kenneyfamily

  • 3 years ago

MAJOR HELP PLEASE!! Verify that the equation is an identity. Show all your work. (sin x + cos x)^2 - 1 = sin 2x

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  1. nubeer
    • 3 years ago
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    (a+b)^2 =a^2+2ab+b^2 so (sin x + cos x)^2 - 1 sin^2x+2sinxcosx+cos^2x -1 2sinxcosx +sin^2x+cos^2x -1 i think u can do from here.

  2. tamtoan
    • 3 years ago
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    use formula \[(a+b)^{2} = a^{2} + 2ab + b^{2}\], expand that out and you will see what you need to

  3. kenneyfamily
    • 3 years ago
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    @nubeer i'm sorry i am a little lost, could you please explain further?

  4. nubeer
    • 3 years ago
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    2sinxcosx +sin^2x+cos^2x -1 have you understood how i have got this part?

  5. kenneyfamily
    • 3 years ago
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    yes with the formula right?

  6. nubeer
    • 3 years ago
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    2sinxcosx +sin^2x+cos^2x -1 what is sin^2x+cos^2x = ?

  7. kenneyfamily
    • 3 years ago
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    1?

  8. nubeer
    • 3 years ago
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    yes.. now put this 1 in the equation 2sinxcosx +sin^2x+cos^2x -1 2sinxcosx +1-1.. got it?

  9. nubeer
    • 3 years ago
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    @kenneyfamily so?

  10. kenneyfamily
    • 3 years ago
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    2sinxcosx

  11. kenneyfamily
    • 3 years ago
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    @nubeer right?

  12. nubeer
    • 3 years ago
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    yes and 2sinxcosx=sin2x (according to the identity)

  13. kenneyfamily
    • 3 years ago
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    you're awesome..thanks!!!

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