1. The problem asks to determine the length of the period of a periodic sinusoidal function given its graph. 2. The period of a sinusoidal function (sine or cosine) is the horizontal length over which the function completes one full cycle and starts repeating. 3. From the graph description, the wave has a maximum peak near 75° and the next peak near 225°. 4. The period $T$ is the difference between these two peak positions: $$T = 225^\circ - 75^\circ = 150^\circ$$ 5. Therefore, the length of the period of the function is $150^\circ$. 6. Among the given options (90°, 300°, 360°, 180°), none exactly matches 150°, but based on the graph, the period is approximately 150°. 7. This suggests the function's period is about 150°, which is not listed, so the closest standard period for sinusoidal functions is 180°. Final answer: The period length is approximately $150^\circ$, closest to $180^\circ$ from the options.