caption: The image shows a plot of a function with a red and blue curve on a white background. The text at the top and bottom of the image reads "Figure 1.1.4 of the fourier curve". The curve is composed of two lines, one in red and one in blue, that intersect at various points on the x-axis and the other at the y-axis. The red line is curved and the blue line is straight, indicating the relationship between the two points.