I saw this video in YouTube since I'm studying for a quiz and found out that the count used for graphing trigonometric functions is 1/4 of a period. Is it always like that?? Sine, cosine, tangent, csc, sec, cot??

thank you

this is the link: https://www.youtube.com/watch?v=yR7y8hyOpDU&spfreload=10 around 6:55


closed as unclear what you're asking by 5xum, Claude Leibovici, Michael Galuza, Dario, user230715 Aug 17 '15 at 7:32

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  • $\begingroup$ Can you provide a link to the video or explain further what you mean by 'count'? $\endgroup$ – Ben Sheller Aug 17 '15 at 5:39
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    $\begingroup$ What video? What count? You need to provide more details. $\endgroup$ – Moti Aug 17 '15 at 5:40
  • $\begingroup$ What's a "count"? $\endgroup$ – 5xum Aug 17 '15 at 5:40
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    $\begingroup$ I'm gonna take a guess and say they mean $\pi/4,\pi/2,3\pi/2,2\pi$. These are the usual angles students are taught to memorize in order to graph trig functions. $\endgroup$ – Rocket Man Aug 17 '15 at 5:41
  • $\begingroup$ @Jill, if AJ Stas above is correct in what you mean by the word 'count,' then the answer to your question is, "No, it isn't always like that." Sometimes we use things like $\pi/6$ or $\pi/3$, it just depends upon the situation. If you provide some more details, we can be of more use. $\endgroup$ – Ben Sheller Aug 17 '15 at 5:44

No, sometimes we use a different 'count,' (in the sense of the guy in the video). If you memorize the value of trigonometric functions evaluated at, say, something like $\frac{\pi}{6}$, then we could use a count of $\frac{1}{6}$ instead. It just depends upon how close together we want the points we are graphing to be. A count of $\frac{1}{4}$ just means that our points are $\frac{\pi}{4}$-ths away from each other.

  • $\begingroup$ how do we usually find the count? Is it usually given or something?? Like if my teacher gave me an equation and told me to graph it, how would I know the graph. $\endgroup$ – Jill Aug 17 '15 at 6:00
  • $\begingroup$ @Jill We usually just take whatever we think is convenient, there is no specific count for a given problem. Usually, we would probably choose $1/4$ or $1/6$, but it depends upon what you are most comfortable with. If you have the value of $\cos(\pi/4)$ memorized but not the value of $\cos(\pi/6)$, for example, you may want to choose a count of $1/4$. Just choose the count so that you are inputting numbers you can actually calculate or have memorized. $\endgroup$ – Ben Sheller Aug 17 '15 at 6:04

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