How can I sketch the graph of y=cos2x?
- rajLv 71 decade agoFavorite Answer
give x the values -pi/4,-pi/3,-pi/6,-pi/2,-pi,pi,6,pi/4,pi/3,pi/2,pi
find the values of cos 2x
take it on the y axis and plot
- LoreleiLv 44 years ago
If you really can't do it, sketch axes, then tap into your calculator the values. So pick x=0. Tap in cos0, cos(2*0). Draw the results on your sketch in different colours Then pick x=30. Tap in cos(30), cos(60) which is cos 2x. Draw the results on your sketch in different colours Then pick x=60. Tap in cos(60), cos(120). Draw the results on your sketch in different colours etc. You'll have your graph.
- HelmutLv 71 decade ago
preferably with a pencil, so you can erase your mistakes.
The acceptable method of graphing any function is to set up a table of solution values, and plot the values on your graph.
You already know that -1 <= y <= 1 and the function repeats every pi radians or 180 degrees, right?
- 1 decade ago
i used y=cos(2x) [i hope that's what you meant]
I get a sine wave with an amplitude of 1 and a wavelength of 3(about 3, a little more acutally)
If you can you might want to scale the y-axis by .25 and the x-axis by .5 or 1/3, that should make it easier to sketch.
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- alrivera_1Lv 41 decade ago
One way to plot this graph is to vary x from [0 to 360 degrees]. If you recall, the period of cosine(x) varies in this range. In this case, you have 2 times the angle x; when you complete this plot, you will find that you will have two complete cycles of cosine x in this period.
Please note that you can also work this problem using radians [0 to 2pi].
- Anonymous1 decade ago
x and y intercepts
From there it should be pretty straightforward. A graph in the interval [-2pi,2pi] should suffice.