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Math Help - y = -3 sin(2t) + cos(2t).. Express in the form A sin(wt+@)

  1. #1
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    y = -3 sin(2t) + cos(2t).. Express in the form A sin(wt+@)

    If possible could someone explain how i go about this? Thanks.

    Express each of the following in the amplitude/phase form C sin(wt + @ )

    (i) y = -3sin(2t) + cos(2t)

    (ii) y = cos(2t) + 3sin(2t)

    Any help in the method would be fantastic
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  2. #2
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    Re: y = -3 sin(2t) + cos(2t).. Express in the form A sin(wt+@)

    You need to use cos(a+ b)= cos(a)cos(b)- sin(a)sin(b). Take b= 2t so that you have cos(a+ 2t)= cos(a)cos(2t)- sin(a)sin(2t). Now what must cos(a) and cos(b) be equal to?
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    Re: y = -3 sin(2t) + cos(2t).. Express in the form A sin(wt+@)

    I am giving you the steps in general I am sure it would help you. In case of doubt please feel free to asky = -3 sin(2t) + cos(2t).. Express in the form      A sin(wt+@)-trigonometry-equation.png
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