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Math Help - using the unit circle

  1. #1
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    using the unit circle

    Find all values of x on [0, 2pi] that satisfy the equation:

    a) 2 cos(x)-1 b) 2sin^2(x) =1

    I think I can somehow use the unit circle for this one, and the 2pi periods of the trig functions to find other possible answers that fit the domain, but I don't really know where to begin.

    I would appreciate any tips,

    Dave
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  2. #2
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    Quote Originally Posted by 2clients View Post
    Find all values of x on [0, 2pi] that satisfy the equation:

    a) 2 cos(x)-1 = ? b) 2sin^2(x) =1
    (b) ...

     <br />
2\sin^2{x} = 1<br />

     <br />
\sin^2{x} = \frac{1}{2}<br />

     <br />
\sin{x} = \pm \frac{1}{\sqrt{2}} = \pm \frac{\sqrt{2}}{2}<br />

     <br />
x = \frac{\pi}{4} \, , \, \frac{3\pi}{4} \, , \, \frac{5\pi}{4} \, , \, \frac{7\pi}{4}<br />
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