Question

What are the important points to graph `y=3cos x`?

Answer 1

I would say the important points are the zeroes, peaks, and troughs from 0 to 2pi radians.

Explanation:

so:
`0`, `pi/2`, `pi`, `3pi/2`, `2pi` Radians
graph{3cosx [-0.73, 19.73, -5.115, 5.115]}
this will let you draw the curve for one full period