Let's take a look at the co tangent graph as it relates to domain. Remember, domain of a function is really just all possible input values. And when we look at a graph, those input values are really just the values on our X axis, right? All those X values which X values correspond to a given. Why value? I could pick an X value here, See that that corresponds to a Y. I could keep going. I could pick all different X values to have them correspond to a Y. But anywhere I reach one of these vertical ascent oats. All of a sudden, there's no why value that's defined. There's an undefined Why value for those given exes. Okay, well, anywhere else exit has a Y. How do I write that as my domain? Okay, well, I'm going to start off saying that the possible X values go across all real numbers when you use that are to define all real numbers, but X cannot equal anywhere. We have a vertical ascent toe and how do we know where that it was? How do I define that? Let's take a second and look at those vertical Assam toast we have asked. Um, totes add it looks like negative two pi negative pie zero pie two pi And you could guess that's going to continue both directions. Three pi four pi five pi Negative three Negative for negative five. It's going to keep going on forever as this graph continues to repeat itself. How I generalize that statement. Okay, well, I'm gonna refer to that as n pi. Hey, where n is just representing an integer there. Okay, so our domain, it's all real numbers, but ex cannot equal n pi where n represents that integer Those are all the possible inputs that we have a defined output for.