Answer:

Step-by-step explanation:
Given

Required
The phase
We have:

Rewrite as:

A cosine function is represented as:

Where:
Phase
By comparison:

Hence, the phase is: 
5/6 is closest to 1 because it it 1/6 away from 1 and is 5/6 away from 0 and is 2/6 away from 1/2 (referring 1/2 as 3/6) Hope this helps!
Oof this one is hard I think it’s 20 mm but I’m not sure