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Homework Help: Maths question

  1. Sep 2, 2010 #1
    1. The problem statement, all variables and given/known data

    Find X?

    Answer: X = 24.6
    2. Relevant equations

    3. The attempt at a solution

    sin(x) = sqrt(1-cos(x)^2)

    1.732^2 cos(x)^2 -1.16^2= 1-cos(x)^2

    There when wrong?
  2. jcsd
  3. Sep 2, 2010 #2


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    Science Advisor
    Homework Helper

    You squared both sides in the first step, right?
    Well, the square of 1.732cos(x)-1.16 is not 1.732^2 cos(x)^2 -1.16^2.
    You can check it: (a - b)² is not a² - b² but (a - b)(a - b), then open up the brackets...
  4. Sep 2, 2010 #3
    ok thx.. mean i can use (a-b)^2=a^2-2ab+b^2?
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