The video tutorial explains how to graph the function Y = -2 sec(πX/2) by first graphing its inverse function, cosine. It covers calculating amplitude and period, graphing the cosine function, and then transforming it into the secant graph by identifying asymptotes and reciprocal points. The tutorial concludes with finalizing the secant graph by erasing the cosine graph used as a guide.

Explain how the secant graph is related to the cosine graph.

What is the significance of the vertical dashed lines in the secant graph?