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Math Help - Solving a Trig equation by graph

  1. #1
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    Solving a Trig equation by graph

    I need to use the graphing calculator to approximate, to three decimal places,for the solutions to the homework problems I am working on, giving all the solutions possible.
    Here are two of the even ones in the book.
    cos(x)=2x^2
    x=?

    cos(x)=x^2/2
    x=?

    I would appreciate an example of any method to use so I can grasp this and finish my homework, so I can study for another class. This website is such a help, we are very fortunate to have a site like this to help us better understand the concepts we are being taught.
    Thank you very much!!
    Keith Stevens
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  2. #2
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    Hello, Keith!

    Use a graphing calculator to approximate the solutions to three decimal places.

    \cos x \:=\:2x^2

    Try graphing y = \cos x and  y = 2x^2

    . . and locate their intersections.

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  3. #3
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    Quote Originally Posted by kcsteven View Post
    I need to use the graphing calculator to approximate...
    Hello,

    which calculator do you use?

    Quote Originally Posted by kcsteven View Post
    ...
    Here are two of the even ones in the book.
    cos(x)=2x^2
    x=?

    ...
    1. Draw the graphs of
    y=2x^2\text{  and  }y=\cos(x)
    on your calculator.
    2. Place the cursor on the intercept of both graphs.
    3. You get indicated the x-value and the y-value of the intercept somewhere on the screen.
    4. Use the zoom-in function of your calculator, until you've got the result as exact as you need it.

    5. First attempt: A(-0.63, 0.81), B(0.63, 0.81)

    EB
    Attached Thumbnails Attached Thumbnails Solving a Trig equation by graph-graph_lsg1.gif  
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