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-   -   Parametric equations (https://www.askmehelpdesk.com/showthread.php?t=101960)

  • Jun 17, 2007, 08:46 AM
    albear
    parametric equations
    x=t-2sint, y=1-2cost

    show that the curve crosses the x axis where t=pi/3 and t=5pi/3

    I understand that you have to solve y=0 but alli can get is t=pi/3
  • Jun 17, 2007, 08:51 AM
    Capuchin
    can't you just put both t's into the equation for y and show that y = 0 and therefor it's crossing the x axis?
  • Jun 17, 2007, 08:52 AM
    galactus
    1 Attachment(s)
    Always graph if at all possible.
  • Jun 17, 2007, 08:56 AM
    albear
    I could but I don't have access to a graph creator and no be cause that would be the wrong way of answering that qn and I wouldn't get marks, I have to solve y=0 which makes cost=1/2 which makes t=pi/3 but I cannot find out how to make it also equal 5pi/3
  • Jun 17, 2007, 08:58 AM
    galactus


    I'd say get familiar with the unit circle. This is the properties of the trig functions you should know.







    If C=0, then

    If C=1, then

    If C=2, then

    and so on...

    Though, anything that exceeds 2Pi you probably can disregard.
  • Jun 17, 2007, 09:06 AM
    albear
    Thank you, guess I need to read up on my C3 then

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