How to plot the graph of f(x)= 10 cos 3x?

1 Answer
Jul 1, 2015

Your function is a cosine function with amplitude 10 and period 2/3pi.

Explanation:

The graph of your function is the same as the one from a "normal" cosine BUT:
1] Amplitude will be 10;
2] Period will be: period=(2pi)/color(red)(3) using the 3 in front of the x in the argument of your cos. This means that your cos is "squeezed", completing an entire oscillation between 0 and 2/3pi instead of between 0 and 2pi!

Graphically:
y=f(x)=10cos(3x)
graph{10(cos(3x)) [-28.88, 28.86, -14.43, 14.45]}

Where you can see the outline of a normal cos function but with amplitude of 10 and period 2/3pi=2.09 rad

I add another plot, easier to "see" (I hope!):
enter image source here