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Simpliflying trig identities please help quiz due tomorrow

  1. Jan 23, 2006 #1
    i had a test and i got a 55 can someone show me how to do these with the steps if possible

    verify each of the folloring trigonomic identities

    1) 2sin^2x - 1/sinx-cosx = sinx+cosx*

    did my steps wrong

    2) cot^2x-cos^2x = cos^2xcot^2x

    didnt get an answer <no clue how to do


    1) 1+tanx/sinx+cosx*

    1+ sec^2x <dont know

    2) (sinx - 1)(tanx+secx)

    i got cot^2x+1 < dont know

    can someone just explain how to do them and work at least one or two out for me so i can pass the quiz thanks alot the one swith the stars " * " are the ones i got the most points of any anyone who would work one of them out for me would be awsome

    thanks in advance
    Last edited: Jan 23, 2006
  2. jcsd
  3. Jan 23, 2006 #2


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    Homework Helper

    For the first one, you must mean:

    (2sin^2x - 1)/(sinx-cosx)

    Try to be clearer with your notation. And what exactly is it that you say is wrong on the next line? Anyway, just expand one of the sin^2's in the numerator into 1-cos^2 and you'll get the difference of two squares, at which point you can factor and cancel.
  4. Jan 23, 2006 #3
    no it suposed to equal that you are suposed to verify that they are equal
  5. Jan 23, 2006 #4

    Math Is Hard

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    Gold Member

    Hey Kevin. Sorry you had a bad time on your test!

    It might be easier for us to read the problems if you use superscript tags to format your exponents. It's really simple to do. Just use the word sup enclosed with [] to begin and the /sup enclosed with [] to end for anything you want to show up raised and small. I think if you hit the reply button you'll see how I did the example below.

    For instance, you could write a double angle formula like this:
    cos 2x = cos2x - sin2x

    Latex is ultimately better, but sometimes this (I think) is a little faster way of writing these things out.
    Last edited: Jan 23, 2006
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