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 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
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 \[\frac{2\pi}{3}\]

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

JenniferSmart1
 one year ago
Best ResponseYou've already chosen the best response.1dw:1360290074055:dw

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

JenniferSmart1
 one year ago
Best ResponseYou've already chosen the best response.1dw:1360290246963:dw

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

JenniferSmart1
 one year ago
Best ResponseYou've already chosen the best response.1it's \[\frac{2\pi}{3}\] for the period

stamp
 one year ago
Best 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.

JenniferSmart1
 one year ago
Best ResponseYou've already chosen the best response.1dw:1360290496676:dw

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

JenniferSmart1
 one year ago
Best ResponseYou've already chosen the best response.1Let's see \[( \frac{\pi}{3} , 3)\] because \[\frac{2\pi}{3\cdot2}\]

stamp
 one year ago
Best ResponseYou've already chosen the best response.1Ok! 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

JenniferSmart1
 one year ago
Best ResponseYou've already chosen the best response.1I'm guessing because its half way between 2pi/3
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