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    The question is
    http://www.examsolutions.net/a-level...estions/q4.gif

    I found out that one answer is 41.2 but I understand there are more. How do I find these? I remember used to doing this and using CAST if anyone know what that is?
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    I did 360-41.2 and got 318.8. That's not in the range. I dont get it?
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    (Original post by Year11guy)
    The question is
    http://www.examsolutions.net/a-level...estions/q4.gif

    I found out that one answer is 41.2 but I understand there are more. How do I find these? I remember used to doing this and using CAST if anyone know what that is?
    When you had 3x-10 = 113.6

    You need to realise that (using CAST) angles with negative cosines are in the second and third quadrants

    Find more angles that have a cosine of -0.4 and add 10, then divide by 3

    Stop if your answer is outside of the range
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    (Original post by TenOfThem)
    When you had 3x-10 = 113.6

    You need to realise that (using CAST) angles with negative cosines are in the second and third quadrants

    Find more angles that have a cosine of -0.4 and add 10, then divide by 3

    Stop if your answer is outside of the range
    I'm sorry but Im still not getting it. I have got 41.2 degrees. Using that, how do I find out the rest?
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    (Original post by Year11guy)
    I'm sorry but Im still not getting it. I have got 41.2 degrees. Using that, how do I find out the rest?
    You don't


    As I said you find the rest by using the 113.6 in the CAST diagram
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    (Original post by TenOfThem)
    You don't


    As I said you find the rest by using the 113.6 in the CAST diagram
    Ok I got 85.5 degrees and 41.2 degrees. 161.2 degrees is an answer but that requires me to do 360+113.578.. which isn't part of CAST?
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    (Original post by Year11guy)
    Ok I got 85.5 degrees and 41.2 degrees. 161.2 degrees is an answer but that requires me to do 360+113.578.. which isn't part of CAST?
    I do not know what you mean isn't part of CAST

    360+113.6 puts you in the second quadrant again so it is fine
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    (Original post by TenOfThem)
    I do not know what you mean isn't part of CAST

    360+113.6 puts you in the second quadrant again so it is fine
    C 360-theta
    A theta
    S 180-theta
    T 10+theta

    Where does 360+theta fit in?
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    (Original post by Year11guy)
    C 360-theta
    A theta
    S 180-theta
    T 180+theta

    Where does 360+theta fit in?
    You can do 360 plus all of those and 720 plus all of those and ... ... ...

    There are infinite solutions
 
 
 
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