 We need to calculate the distance between our earthquake and each station that recorded the tsunami So the way to do that is to use the great circle path formula and Here is the formula, okay? The cosine of the distance equals the following So in this formula a is the latitude of one of our stations We'll call the latitude of the earthquake b is the latitude of the other point here a Latitude b latitude and c is the difference between their longitudes take the absolute value of that So you're gonna take the sine of this number the sine of this number Now you're gonna take the cosine of this number and the cosine of this number and you're gonna subtract the longitudes from each other It doesn't matter which because you're gonna take the absolute value of that and Take the cosine of that multiply all the co-signs together multiply the signs together add those to And then you have to take the inverse cosine of the answer and you look at the distance in degrees, then you multiply by 1, 1, 1.32, and you look at the distance in kilometers. Now, here are the things that I want to point out that are important. It is important that you know that when you calculate the distance between two points on the surface of a sphere, you need to use the great circle path formula. And I think it's important that you know what that formula is, and I wrote it down right here. But this class is not really meant to be about calculator skills. So if you can automate this in a spreadsheet program or whatever, or you know of a website that will calculate it for you, then that's what you should use because it will actually minimize the errors of you typing stuff in. I've found a good website that works, and this is it. I've given you the link to this in the course five pages. But you need to be smart about using websites just like you would if you were looking up information on a website. And that is, you should do a couple of problems yourself and trust your own math and then check if the website gives you the same answer or not. And I have checked with this one. So here I've entered in the latitude and longitude of the earthquake and the latitude and longitude of our station, and it gives me the distance. It is important when you use a website like this one that if you have points that are in west longitude or south latitude that you enter them in here as negative numbers or else you won't get the right answer. But I wrote all those down correctly for you and your table of values, so hopefully that won't trip you up. Alright, that's all there is to it.