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What is the amplitude, period, phase shift, and midline of f(x) = −3 sin(4x − π) + 2?

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5 votes

\bf \qquad \qquad \qquad \qquad \textit{function transformations} \\ \quad \\ % function transformations for trigonometric functions \begin{array}{rllll} % left side templates f(x)=&{{ A}}sin({{ B}}x+{{ C}})+{{ D}} \\\\ f(x)=&{{ A}}cos({{ B}}x+{{ C}})+{{ D}}\\\\ f(x)=&{{ A}}tan({{ B}}x+{{ C}})+{{ D}} \end{array}


\bf \begin{array}{llll} % right side info \bullet \textit{ stretches or shrinks}\\ \quad \textit{horizontally by amplitude } |{{ A}}|\\\\ \bullet \textit{ horizontal shift by }\frac{{{ C}}}{{{ B}}}\\ \qquad if\ \frac{{{ C}}}{{{ B}}}\textit{ is negative, to the right}\\\\ \qquad if\ \frac{{{ C}}}{{{ B}}}\textit{ is positive, to the left}\\\\ \bullet \textit{vertical shift by }{{ D}}\\ \end{array}


\bf \begin{array}{llll} \qquad if\ {{ D}}\textit{ is negative, downwards}\\\\ \qquad if\ {{ D}}\textit{ is positive, upwards}\\\\ \bullet \textit{function period or frequency}\\ \qquad \frac{2\pi }{{{ B}}}\ for\ cos(\theta),\ sin(\theta),\ sec(\theta),\ csc(\theta)\\\\ \qquad \frac{\pi }{{{ B}}}\ for\ tan(\theta),\ cot(\theta) \end{array}


now, with that template above in mind, let's take a peek of yours


\bf \begin{array}{lcllcclll} f(x)=&-3&sin(&4x&-\pi)&+2\\ &\uparrow &&\uparrow &\uparrow &\uparrow\\ &A&&B&C&D \end{array}

now, as far as the midline, well, the midline for sin(x) is just the x-axis, notice this one, has a D vertical shift, so the midline moved up that much
User Maybeshewill
by
7.5k points
6 votes

Answer:


Amplitude=3


Period=(\pi)/(2)


\text{Phase shift}=(\pi)/(4)


Midline=2

Explanation:

The general sine function is defined as


g(x)=A\sin (Bx+C)+D .... (1)

where, |A| is amplitude,
(2\pi)/(B) is period, -C/B is phase shift and D is midline.

The given function is


f(x)=-3\sin (4x-\pi)+2 .... (2)

On comparing (1) and (2), we get


A=-3


B=4


C=-\pi


D=2

Using these values we can say that


Amplitude=|A|=|-3|=3


Period=(2\pi)/(B)\Rightarrow (2\pi)/(4)=(\pi)/(2)


\text{Phase shift}=-(C)/(B)\Rightarrow -(-\pi)/(4)=(\pi)/(4)


Midline=D=2

Therefore,
Amplitude=3,
Period=(\pi)/(2),
\text{Phase shift}=(\pi)/(4) and
Midline=2.

User Dortique
by
7.2k points