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sdlinsey · Apr 26, 2009, 03:33 PM

15) Period of y = cos 3x

Perito · Apr 26, 2009, 03:48 PM

One way is probably to generate a graph.

$y=cos(3x)$

The cosine function has a period of $2\pi$ . If you multiply "x" by 3, the function will repeat (cycle) three times as x goes from 0 to $2\pi$ . Therefore, the period is $\frac {2 \pi}{3}$ .

Here's a link to help you visualize it.

Cosine Function

Click on the "Click here to start" button and move the sliders.

The amplitude is the same as the normal cosine function (range -1 to +1). If you wished to change that, you'd have to multiply the cosine function by something.

Unknown008 · Apr 26, 2009, 07:28 PM

Ok, just remember that in a given function y = a cos (bx) +c or y = a sin (bx) + c,

The amplitude will be given by a,

The period will be given by $\frac{360}{b}$ or $\frac{2\pi}{b}$