graph y=1/2*cos(3ø+m/3)

Question

I just need someone to explain how to do this 

Answer 1

I assume you're in a trigonometry course and are at the point where the textbook (I hope you have one) is dealing with amplitude, period and phase shift.

 

At this juncture I must ask if the "m/3" is intended to be pi/3--a phase shift.

 

The 3 that is coefficient of φ changes the period to 2pi/3.  The factor ½ reduces the amplitude from 1 to 0.5.

 

The (assumed) pi/3 addition to 3φ is a phase shift; set 3φ + pi/3 = 0 to find out the value of φ to which the 'beginning' value of cos 0 has been relocated to (it's left shift, pi/9 on the φ-axis.