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how do I graph \[y=3cos(3x)\]?
I know that 3 is the amplitude
I know that the graph will be upside down.
I know that the period is \[\frac{2\pi}{3}\]
 one year ago
 one year ago
how do I graph \[y=3cos(3x)\]? I know that 3 is the amplitude I know that the graph will be upside down. I know that the period is \[\frac{2\pi}{3}\]
 one year ago
 one year ago

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stampBest ResponseYou've already chosen the best response.1
Copy the image and begin by marking your amplitude, the highest and lowest point of the wave.dw:1360290026921:dw
 one year ago

JenniferSmart1Best ResponseYou've already chosen the best response.1
dw:1360290074055:dw
 one year ago

stampBest ResponseYou've already chosen the best response.1
now label \[(\frac{2\pi}{3},f(\frac{2\pi}{3}))\]this point is the end of your period.
 one year ago

JenniferSmart1Best ResponseYou've already chosen the best response.1
dw:1360290246963:dw
 one year ago

stampBest ResponseYou've already chosen the best response.1
\[f(x)=3cos(3x)\]\[f(\frac{3\pi}{2})=3cos(3(\frac{3\pi}{2}))=3cos(9\pi/2)\]
 one year ago

JenniferSmart1Best ResponseYou've already chosen the best response.1
it's \[\frac{2\pi}{3}\] for the period
 one year ago

stampBest ResponseYou've already chosen the best response.1
@JenniferSmart1 My fault. You evaluated it correctly, I would have gotten 0 for f(3pi/2) while f(2pi/3) is 3. Ok, so now can you finish the graph from here? So far you have done an excellent job.
 one year ago

JenniferSmart1Best ResponseYou've already chosen the best response.1
dw:1360290496676:dw
 one year ago

stampBest ResponseYou've already chosen the best response.1
Could we label the highest point (x, f(x)) if we were asked?
 one year ago

JenniferSmart1Best ResponseYou've already chosen the best response.1
Let's see \[( \frac{\pi}{3} , 3)\] because \[\frac{2\pi}{3\cdot2}\]
 one year ago

stampBest ResponseYou've already chosen the best response.1
Ok! I think your graph seems pretty complete, well done. Here is the actual graph for reference http://www.wolframalpha.com/input/?i=3cos%283x%29
 one year ago

JenniferSmart1Best ResponseYou've already chosen the best response.1
I'm guessing because its half way between 2pi/3
 one year ago
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