Graph y=-2sin(2x)
Problem
Solution
Identify the amplitude. The amplitude is the absolute value of the coefficient of the sine function,
|a|=|−2|=2 This means the graph oscillates betweeny=2 andy=−2 Determine the period. The period
P of a sine functiony=a*sin(b*x) is calculated using the formulaP=(2*π)/b Here,b=2 soP=(2*π)/2=π Find the phase shift and vertical shift. Since there are no horizontal or vertical translations added to the argument or the function, the phase shift is
0 and the vertical shift is0 Identify key points. Divide the period into four equal intervals of length
π/4 Starting fromx=0 the keyx values are0,π/4,π/2,(3*π)/4,π Calculate the y-coordinates. Evaluate the function at the key
x values:
At
x=0 y=−2*sin(0)=0 At
x=π/4 y=−2*sin(π/2)=−2 At
x=π/2 y=−2*sin(π)=0 At
x=(3*π)/4 y=−2*sin((3*π)/2)=2 At
x=π y=−2*sin(2*π)=0
Sketch the graph. Plot the points
(0,0) (π/4,−2) (π/2,0) ((3*π)/4,2) and(π,0) and connect them with a smooth sine wave. Note that the negative sign in front of the amplitude causes the graph to be reflected across thex axis compared to a standard sine wave.
Final Answer
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