Math Grade 11 Sinusoidal functions
Sinusoidal functions. math grade 11.
#1) Determine the equation of each graph in the form y = acos(bx).
#2) Determine the equation of each graph in the form of y = asin (bx).
Both Graphs are not posted here, but i have a link for each graph below:
Graph 1. http://i515.photobucket.com/albums/t358/moeen11/latest.png
Graph 2. http://i515.photobucket.com/albums/t358/moeen11/lates1.png
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We are asked to only answer 1 question, but you should be able to answer the other using similar reasoning:
In graph 1 we see that there is a maximum at y=4, a minimum at y=-4, and the period is 1440. We are asked to write an equation for the sinusoid as a transformation of the cos graph and the sin graph.
(1) The graph is already in the shape of the cos, so we will begin there.
The general form is `y=Acos(B(x-h))+k` where A gives the amplitude (and if A<0 it reflects the graph across the horizontal axis), the period is found from B (`p=(360)/B` ), h is a horizontal translation (phase shift) and k is a vertical translation (its effect is to move the midline.)
Since the max is 4 and the min is -4, the midline is `y=(4+-4)/2==>y=0` so k=0. Also the amplitude is `A=(4-(-4))/2=4`
The graph is already in the proper position for the cos, so there is no phase shift. The period is ``1440, so `B=360/p=360/1440=1/4`
Thus the equation is `y=4cos(x/4)`
(2) In order to write the equation in terms of sin, we realize that the period and amplitude stay the same as well as the lack of vertical translation. There is only a phase shift to deal with.
The phase shift is 90 to the left, so the equation is `y=sin(x/4+90)`
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