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How do I draw this graph? Eg. $\cos\pi$ starts at y=1, flows down to x=$\pi$ as the mid point where y=-1 and goes back to y=1.

I'm not sure how to decipher the $2\pi10t$ here and put them into figures in a graph.

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    @anon Not sure about y=$cosx$. I know $y=f(x)$ and $y=f(ax)$. Period of $cos 2\pi10t$ is 1/10 as given by Henry below?2012-05-08

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You probably know the basic shape of a cosine curve.

$\cos x$ is $1$ when $x=0$, is $0$ when $x=\pi/2$, is $-1$ when $x=\pi$, is $0$ when $x=3\pi/2$, and is $1$ when $x=2\pi$, and then the pattern repeats.

So $\cos (2\pi 10 t)$ is $1$ when $t=0$, is $0$ when $t=1/40$, is $-1$ when $t=1/20$, is $0$ when $t=3/40$, and is $1$ when $t=1/10$, and then the pattern repeats.

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    @resting: No. When $t=\frac{1}{10}$ you get: $10t=1$; $2\pi 10 t=2\pi$; and $\cos (2\pi 10 t)=\cos(2\pi)=1$.2012-05-08