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The general form of transformed sine and cosine functions are y=asin b(x-l)+k and y=a cos b(x-l)+k. Determine whether the graph is modeled by a sine or a cosine function, and then find the values of a, b, l, and k.
h = - 36.25 cos (Ď€/12 t) + 34.25
We are told that the highest point of a bucket on the wheel is 70.5 feet above the viewing platform and the lowest point is - 2. We want to write a model for the height of the bucket as a function of time t. To do so, we will consider the general forms of transformed sine and cosine functions. Sine Function:& y= asin b(x- l)+ k Cosine Function:& y= acos b(x- l)+ k In these functions | a| is the amplitude, 2Ď€ b is the period ( b>0), l is the horizontal shift, and k is the vertical shift. To write a function of a sinusoid, we will follow four steps.
Let's follow these steps one at a time!
a+(- b)=a-b
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Since the minimum point occurs at t=0, the function passes through y-axis at its minimum point. Then, the height can be modeled as a cosine function reflected across the x-axis and with no horizontal shift. This means that l= 0.
a-(- b)=a+b
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Because of the location of the minimum point, we concluded that the height should be modeled by a cosine function. We also found that a= - 36.25, b= π12, l= 0, and k= 34.25. Finally, we can write the equation of the model. h = - 36.25 cos π/12( t - 0)+ 34.25 ⇕ h=- 36.25 cos π/12 t + 34.25