 Now we need to find X. How are we going to find X? Well, I'm going to erase some of this stuff. Let's erase this one, since we know the sum of the angles is 3, 6, is 180, and let's erase this one because we know there's six pieces of info right now. So, we need to find X. There's two ways. Actually, now there is six ways. Actually, one, two, three, four different ways you can find X. You can use the Pythagorean theorem, and the relationship with the Pythagorean theorem is a squared plus b squared equals c squared. What this means is one leg of a triangle squared, of a right angle triangle squared, plus the other leg of the triangle squared is equal to the hypotenuse squared. So, the way this works is over here, a and b always refer to the two sides that aren't the hypotenuse. So, you can call this one a or this one a. It doesn't make a difference. So, let's just go with the X being a. So, it's going to be a squared plus b squared equals c squared. So, it's going to be x squared plus 3.5 squared is equal to 7 squared. So, all you're going to try to do is get x by itself now. So, again, you're going to grab your calculator because 3.5 is a, you know, it's not a clean number. You don't know what 3.5 squared is. It was 3. You know it was 9 because you know your multiplication table, right? So, what you're going to do is go 3.5 squared is a, that's too many times, 3.5 squared is 12.25. So, you got x squared plus 12.25 is equal to 7 squared is 49. Now, you're going to get x by itself, right? So, you're going to grab this guy, bring it over. It was a plus here, it comes a minus here. So, it's going to be x squared is equal to 49 minus 12.5, 12.25, okay? I'm just going to erase these guys so we've got more room. So, 49, 49 minus 12.25 is 36.75. So, right now, we've got x squared is equal to 36.75. Now, you got x squared equals this. You don't need x squared. You want to find out what x is. So, the way you get x by itself is you do the opposite of squared. The opposite of something squared is a square root. So, you take the square root of both sides. Square root of x squared is x. Square root of 36.75 is 6.06. So, x is 6.06. y was 3.5. And you solve that one because the sum of the angles was 180. You subtracted those two to get that one. Now, whenever you're dealing with triangles, you can do a quick check to make sure you did things correctly because, as we talked about, the side for a triangle, the angle controls the side. So, that means if this is the smallest angle, then this has to be the smallest side. If this is the biggest angle, then this has to be the biggest side, okay? So, for over here, when you're taking a look at these guys, the smallest angle is 30. So, the smallest side has to be a cross from the smallest angle, which is 3.5. The biggest angle is 90. And the biggest side is 7. The middle angle is 60. And this is the middle side. So, that's a mental note. If you had this backwards, let's say this was 8.5 when you solve for it, you would know you did something wrong because that's a cross from the smallest angle. It can't be 8.5. The hypotenuse has to be the biggest side because that's 90 degrees. So, you would know you did something wrong. You would have to redo it, okay? Find out where you got things wrong, okay? So, that's the quick, just a quick intro of dealing with right angle triangles. I'm going to do a couple more of these things, solve these triangles. So, for you to get an idea of exactly how to do it and how many different variations it can give you, okay? I'm going to drop a couple more, a couple more of these guys and we'll see where we go, okay?