Question

What is the period of the parent cosine function, y = cos(x)?

Answer 1

Answer:

The next one is a horizontal stretch

Answer 2

We have to find the period of the parent cosine function and the period of the function showed on the graph.
Period = 2π / B, where B is the coefficient of x - term.
1. For the function: y = cos x,  B = 1
Period = 2 π / 1 = 2 π = 360°.
2. For the graphed function ( from the picture ):
Period = 6 π = 1,080°