The graph in the image shows a trigonometric function. Let's analyze it carefully:

• The function starts at 1 when $x = 0$, and then it decreases to -1 and back to 1, completing one full cycle by $x = 360^\circ$.
• This behavior is characteristic of a cosine function.
• The period of the function is 360 degrees, which is typical for a cosine function with no horizontal stretch or compression.
• The amplitude (the height from the midline to the peak) is 1, and the graph goes from 1 to -1 and back to 1.

Based on these observations, the function displayed appears to be $\cos(2x)$, which matches option B.

Would you like more details on how the cosine function works or further explanations?

Here are 5 related questions to think about:

1. What would the graph of $\sin(2x)$ look like compared to $\cos(2x)$?
2. How does changing the coefficient of $x$ in $\cos(kx)$ affect the graph?
3. What happens if we change the amplitude of the function $\cos(kx)$?
4. How would the graph of $\cos(x/2)$ compare to $\cos(2x)$?
5. What is the phase shift in trigonometric graphs, and how would it affect $\cos(x)$?

Tip: When identifying trigonometric graphs, pay attention to the starting point, the amplitude, and the period to match them to the correct function.