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Trigonometric Functionssimplify sin squared functions

  1. Sep 12, 2006 #1
    just looking at another question to do with trigonometric functions and I cant see how they simplify the follwing:
    2sin^2x-3sinx-2=0 to
    again i prob thinking sumthin really stupid...but i cant see wat!!! cheers
  2. jcsd
  3. Sep 12, 2006 #2
    The equation can be treated like a normal quadratic equation.

    use substitution and replace "sinx" with "x"
    2(sinx)^2-3sinx-2=0 ----> 2x^2-3x-2=0

    factor the equation
    2x^2-3x-2=0 = (2x+1)(x-2)

    Replace "x" with "sinx"
    (2x+1)(x-2)=0 -----> (2sinx+1)(sinx-2)=0

    If you aren't allowed to use this method and you have to use trig identities then someone else will have to help. I'm too lazy to look up or derive the identities right now :-p
  4. Sep 12, 2006 #3
    cheers mate...and i like ur thinkin!!!! LOL
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