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C2 Trigonometric Graph Question (OCR June 2015 past paper) Watch

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Size:  102.1 KB Hi, I've been doing some C2 Past papers, and I've come across quite a tricky question on the most recent Ocr paper. I'm not really sure where to start in tackling this one.

    If anyone could point me in the right direction it would be appreciated!

    Edit - question is in the photo attached.
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    (Original post by sknmaster)
    Name:  ocrq9.png
Views: 163
Size:  102.1 KB Hi, I've been doing some C2 Past papers, and I've come across quite a tricky question on the most recent Ocr paper. I'm not really sure where to start in tackling this one.

    If anyone could point me in the right direction it would be appreciated!

    Edit - question is in the photo attached.
    It's just testing your knowledge of the trigonometric graphs; so, for example, if \alpha is a solution to the given equation, then - by the symmetry of the cosine graph so is 2\pi - \alpha.

    It might help to mark these points on your graph as well as mark the roots of the cosine graph as \frac{\pi}{2}, \frac{3\pi}{2} and the minimum at -\pi.

    For the next bit of the question ,try drawing the line y=-k, what do you think the solution is? Is it going to be \pi + \alpha or \pi - \alpha, etc...

    Does that help?
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    (Original post by Zacken)
    It's just testing your knowledge of the trigonometric graphs; so, for example, if \alpha is a solution to the given equation, then - by the symmetry of the cosine graph so is 2\pi - \alpha.

    It might help to mark these points on your graph as well as mark the roots of the cosine graph as \frac{\pi}{2}, \frac{3\pi}{2} and the minimum at -\pi.

    For the next bit of the question ,try drawing the line y=-k, what do you think the solution is? Is it going to be \pi + \alpha or \pi - \alpha, etc...

    Does that help?
    yes, took some time but i understand it now!

    just to check, ordinarily the cos curve in this example would have a period of 2pi, but since the curve is 2tan1/3, there has been a stretch (affecting the x axis roots) as well as a vertical stretch of scale factor 2, meaning the period is now 6pi?
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    (Original post by sknmaster)
    yes, took some time but i understand it now!

    just to check, ordinarily the cos curve in this example would have a period of 2pi, but since the curve is 2tan1/3, there has been a stretch (affecting the x axis roots) as well as a vertical stretch of scale factor 2, meaning the period is now 6pi?
    Nopes, the the curve \cos \left(ax\right) has period \frac{2\pi}{a}.
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    Check out AZ TUTORING on You Tube they have got a lot of past paper exam questions on maths a level

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