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Math Help - How to show work (Unit circle)

  1. #1
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    How to show work (Unit circle)

    Can someone please help me out with this question.


    Find all the possible angles for A if 0 ≤ A ≤ 2 (pi)

    I) cosA = -1/(square root of 2)


    Alright so I know the answer is 3pi/2 and 5pi/2..



    How would I show the work to solve for thsee problems though? Thanks for the help
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  2. #2
    Super Member 11rdc11's Avatar
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    Check again beacuse \cos{x} = -\frac{\sqrt{2}}{2} at 135 and at 225 degrees
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  3. #3
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    are you sure?? I have a test on this soon and this is from hwk throughout the course... I have a website that the teacher gave which says otherwise..

    http://math.hhpnet.com/mhf4u1/downlo...ngles%20II.pdf


    It's for question 2 a)...


    I ahve the answers but I want to know how to solve problems like these without the answers , and mainly the steps to get the answer.


    Thanks
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  4. #4
    Super Member 11rdc11's Avatar
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    Quote Originally Posted by agent2421 View Post
    are you sure?? I have a test on this soon and this is from hwk throughout the course... I have a website that the teacher gave which says otherwise..

    http://math.hhpnet.com/mhf4u1/downlo...ngles%20II.pdf


    It's for question 2 a)...


    I ahve the answers but I want to know how to solve problems like these without the answers , and mainly the steps to get the answer.


    Thanks
    I could not open the link due to my secruity settings but yep I'm sure I'm right.

    What you have to remember is the values for cos x

    \cos{0} = 1

    \cos{30} = \frac{\sqrt{3}}{2}

    \cos{45} = \frac{\sqrt{2}}{2}

    \cos{60} = \frac{1}{2}

    \cos{90} = 0

    Now use reference angles to to determine what the degree would be. It would have to be in the 2nd and 3rd quad since x is negative.
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