Question

How do I draw the curve of 2cos(3x)? And also the curve cos(x/3)?

Answer 1

2 is the amplitude and 3 is the frequency. You need to modify a regular cosine graph to be pulled vertically between 2 and -2 and compress it so that it does 3 cycles in 2pi.

With cos(x/3) the only change you make to a regular cosine graph is to stretch it out along the x axis so that it is 3 times as long; or rather 1 complete cycle is 6pi.

Answer 2

Ah yes! Fantastic! I get it now! Thanks very much! :)