Find the amplitude, period, and phase shift of the functions, then graph:
a) y = cos2(x-pi/2)
b) y = 2 sin (1/2 x - Pi/6)
How can I graph this by making the x-axis values, pi, pi over 3, 5 pi over 6 and other radian values?
1 Answer | Add Yours
Given a sinusoid in the form `y=AsinB(x-h)+k` :
(1)Start with the basic function (sin or cos)
(2) "A" affects the amplitude; instead of` ` an amplitude of 1, the transformed function has an amplitude of A. (This is measured off of the midline). "A" is a vertical dilation. If A<0, then the function is reflected over a horizontal axis.
(3) "B" affects the period. For sin and cos, the original period is `2pi` . The period of the transformed function will be `(2pi)/B` . "B" performs a horizontal dilation. If B<0 the function is reflected over a vertical axis. This is a phase shift.
(4) "h" tranlates the function left/right.
(5) "k" translates the function up/down.
P1) `y=2cos(x-(pi)/2)` .
-- Since A=2 the amplitude is 2.
-- Since `h=pi/2` the function is shifted right `pi/2` units.
-- the period is `2pi` (unchanged)
The highest point on the graph will be y=2, the lowest y=-2. Some points:
`(pi/2,2),((2pi)/3,sqrt(3)),((3pi)/4,sqrt(2)),((5pi)/6,1),(pi,0),((7pi)/6,-1)` etc... From the original values for cos, add `pi/2` to the x-values, then double the corresponding y-values. (Original point on cosx is (0,1). Add `pi/2` to 0 and double 1 to get the transformed point `(pi/2,2)` )
This can be written as `y=2sin (1/2) (x-pi/3)` . In this form we see that A=2,B=1/2 and `h=pi/3` .
-- the amplitude is 2
-- the period is `(2pi)/(1/2)=4pi`
-- the phase shift is `pi/3` to the right.
` `` `
We’ve answered 317,368 questions. We can answer yours, too.Ask a question