 This video is just a quick review of trigonometry in which you learned about sine, cosine, and tangent in yesterday's videos. So let's just do a really quick review here and remember that we can use Soka Toa to help us remember sine, cosine, and tangent. So I'm just going to write it up here. Sine, and so I use s, is equal to opposite over hypotenuse. So that's so Ca, cosine, is equal to adjacent over hypotenuse, and Toa, tan, is equal to opposite over adjacent. So that's what I'm going to use to help me figure out problems 1 through 6. You'll notice that the directions ask us to write the trigonometric function for the given angle that would use the given ratio. So basically we're working backwards here, and we are given the ratio, and we're given which angle we need to figure out if it's sine, cosine, or tangent. So let's take a look at number 1. We should be looking at angle x, and we have b, which is the adjacent side, and c, which is the hypotenuse. Remember the hypotenuse is always opposite the 90 degree angle. So which of our three trig functions would be adjacent over hypotenuse? And so I can look up here, and I see adjacent over hypotenuse. So therefore this would be cosine. Whoops. Okay. Now we're going to do the same thing. I'm just gonna erase, I guess it's not gonna let me erase that, never mind. I'll change colors then. And in this next one, we are still looking at angle x, so we're still here. This time we want a over c. So if I look at my picture, a is opposite, and c is still the hypotenuse. So if I look up at my three trig functions, so katoa, opposite over hypotenuse is sine. So therefore this one is the sine of x is equal to a over c. And the last one we have, again still looking at angle x, right here. And this time it's equal to a over b. So a is opposite, b is adjacent, and so the one that we have left obviously opposite over adjacent right here is tangent. So this would be tan. Now we're going to do the same thing, but you'll notice that we have changed the angle that we're looking at. So now in four, five, and six, the angle that we're dealing with is y. So that just means that you're going to change where you're looking. So now we're looking at angle y, which is this angle right here, and the first one, number four, is b over a. So b is opposite, and a is adjacent. So opposite over adjacent would be tangent. The next one is a over c. So if I'm again looking at angle y, a is adjacent, and c is the hypotenuse. So adjacent over hypotenuse is cosine. And then b over c, again, we're still looking at angle y. So b is opposite, and c is hypotenuse, which leaves us with sine. Now we are going to, in the videos today, we're going to talk about inverses of sine, cosine, and tangent. So keep these review questions in mind as you watch the rest of the videos.