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Thread: Maths help???

  1. #1
    I do things like get in a taxi and say, "The library, and step on it. Lord's Avatar
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    Default Maths help???

    Pretty easy I think but I was out sick when they did it in school and none of the trigonometric examples in my book cover this:

    How does sin 2 a = 2sinacosa
    Well, I open my eyes and I see things. I've seen spirits moving through the walls. I've seen a vortex coming through the wall. I've seen amorphous little balls of light bouncing all around in the front yard through the window. I've seen giant bugs on the floor. I was in a hotel room in Amarillo, Texas, and all I remember is standing on the bed and seeing the whole wall in front of me filled with lights that were [makes popping sound] popping like popcorn out of the wall. Then I'll wake up and I go "Wow, I was standing on my bed and staring at this wall."

  2. #2
    what about .. eyebrows God's Avatar
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    what do you mean. what values of a satisfy(all of them) or a proof of the identity (use sin(x+y) = sinxcox + sinycosy)

  3. #3
    princeso Kirby's Avatar
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    Its a double angle identity. This is my only idea of how to prove it involves a sum to product function but I keep on running into dead ends.

  4. #4
    princeso Kirby's Avatar
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    maybe

    2sin(a)cos(a)
    2(1/2(sin(a+a)+sin(a-a))): product to sum formula
    sin(2a)+sin(0)
    sin(2a)+0
    sin(2a)

    thats the closest I can get

  5. #5
    what about .. eyebrows God's Avatar
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    sin(x+x) = sinxcox + sinxcox = 2sinxcosx = sin(2x)

    also i mistyped the identity in my first post its sinxcosy + cosxsiny

  6. #6
    I do things like get in a taxi and say, "The library, and step on it. Lord's Avatar
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    It's a proof of identity question.

  7. #7
    I do things like get in a taxi and say, "The library, and step on it. Lord's Avatar
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    Quote Originally Posted by God View Post
    sin(x+x) = sinxcox + sinxcox = 2sinxcosx = sin(2x)

    also i mistyped the identity in my first post its sinxcosy + cosxsiny
    That looks right but it also looks way too simple to be the answer. Is there a way we can throw the sin rule/cosine rule/angle formula in the middle to prove of or something?

  8. #8
    princeso Kirby's Avatar
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    so lord, do I just not exist or something

  9. #9
    The One and Only trixie's Avatar
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    Why do you want it to be complex, Lord? It has a very simple answer, that is the elegance of Math.
    Originally made by LM:


    ~ I have said nothing because there is nothing I can say that would describe how I feel as perfectly as you deserve it. -- Kyle Schmidt ~

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  10. #10
    Registered Users Regular Flaming Flamingo's Avatar
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    Everytime I see this thread I read it as Meths help

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