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    Say if they gave this question

    Solve cosX=0 for -30 < X < 690*

    I may have to sketch a complete graph of cosX for -30 < X < 690*, or even just 0 < X <690*. Then I'd find the values of X for which y=0 in the range.

    But is it okay if I do this:
    sketch a graph of cosX for only 0<X<360* and then find the X values for which y=0 in that range.
    say that cosX graph has period of 360* and then give all the solutions of X.

    ?? Would I lose marks through this method if it was an exam question?

    Thanks
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    (Original post by krisshP)
    Say if they gave this question

    Solve cosX=0 for -30 < X < 690*

    I may have to sketch a complete graph of cosX for -30 < X < 690*, or even just 0 < X <690*. Then I'd find the values of X for which y=0 in the range.

    But is it okay if I do this:
    sketch a graph of cosX for only 0<X<360* and then find the X values for which y=0 in that range.
    say that cosX graph has period of 360* and then give all the solutions of X.

    ?? Would I lose marks through this method if it was an exam question?

    Thanks
    You'll be given full credit for any well-structured answer, with ample justification throughout, that gives you all of the solutions
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    (Original post by krisshP)
    Say if they gave this question

    Solve cosX=0 for -30 < X < 690*

    I may have to sketch a complete graph of cosX for -30 < X < 690*, or even just 0 < X <690*. Then I'd find the values of X for which y=0 in the range.

    But is it okay if I do this:
    sketch a graph of cosX for only 0<X<360* and then find the X values for which y=0 in that range.
    say that cosX graph has period of 360* and then give all the solutions of X.

    ?? Would I lose marks through this method if it was an exam question?

    Thanks
    It is possible that some examiners would take marks off in C2 but I am not certain about this. For this example though, if cos(x) = 0 \Rightarrow x = 2n\pi \pm \frac{\pi}{2}
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    (Original post by Indeterminate)
    You'll be given full credit for any well-structured answer, with ample justification throughout, that gives you all of the solutions
    Thanks
 
 
 
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