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Math Help - The amplitude of a sine graph

  1. #1
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    The amplitude of a sine graph

    Hi, I'm just going through a practice exam and looking over my answers compared to the answer key.

    y=3sin(x+\frac{\pi}{3}) - 1

    It asked for the range of the function in interval notation.
    I put down [-1, 2], because I figured the amplitude was 3?

    But the answer is [-4, 2]

    I need some clarification as to why. Am I missing something? Do I multiply the amplitude by 2 or something weird?

    Thanks in advanced.
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  2. #2
    Behold, the power of SARDINES!
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    Quote Originally Posted by tiar View Post
    Hi, I'm just going through a practice exam and looking over my answers compared to the answer key.

    y=3sin(x+\frac{\pi}{3}) - 1

    It asked for the range of the function in interval notation.
    I put down [-1, 2], because I figured the amplitude was 3?

    But the answer is [-4, 2]

    I need some clarification as to why. Am I missing something? Do I multiply the amplitude by 2 or something weird?

    Thanks in advanced.
    Remember that the sine function goes both up and down.

    Here is a graph I hope it clears it up

    Attachment 11033
    Attached Thumbnails Attached Thumbnails The amplitude of a sine graph-capture.jpg  
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  3. #3
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    Quote Originally Posted by TheEmptySet View Post
    Remember that the sine function goes both up and down.

    Here is a graph I hope it clears it up

    Attachment 11033

    OH! So the amplitude is between [-3, 3] but because of our shift down it's [-4, 2].

    HAHA okay, thanks so much!!!!!
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