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Math Help - lets see if you can get this beast

  1. #16
    Junior Member winterwyrm's Avatar
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    why does y= x-1 though?
    Last edited by winterwyrm; October 20th 2007 at 03:30 PM.
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  2. #17
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by winterwyrm View Post
    why does y= x-1 though?
    There are two reasons, not entirely independent.
    1) He wanted the limit to go to 0 so he could use his approximation for the cotangent.

    2) It works. That's pretty much the final reason for using any method.

    -Dan
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  3. #18
    Grand Panjandrum
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    Quote Originally Posted by winterwyrm View Post
    why does y= x-1 though?
    As topsquark says, basically I want to use small angle approximations for the
    trig function, and this substitution makes it easier to see what I am doing.

    Also If I wanted to do a power series expansion, then if the limiting variable
    is going to zero and I have expanded about 0, then I can discard the higher
    order terms (but this is essentially the same reason as above).

    Unless the limit is obvious it is the first move I normally make.

    RonL
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