 This video is called Using Ratios to Find Angles of Triangles. It's important to read the instructions for this problem so you know how to approach it correctly. It says, find the measures of the angles of a triangle with the ratio of two to three to four. The two to three to four is representing the three side lengths of a triangle with the two representing one side, the three representing another, and the fourth representing the last side of a triangle. So let's think about this for a minute. Measures of the angles of a triangle, they all add up to 180 degrees. The ratios, well one side can be represented by a 2x, the second side can be represented by a 3x, and the last side can be represented by a 4x. And what will they all add up to equal? Well, what we just talked about, 180 degrees. So now, if I simply add up those three angle measures, set them equal to 180, I'll be able to solve for x, and then therefore go ahead and get the angle measures for my triangle. So let's go ahead and clean up this problem. The left-hand side, 2 plus 3 gives me 5, 5 plus 4 gives me 9, so I have 9x equals 180. When I divide both sides by 9, x gives me 20. So that's great, but be careful, you're not done with this problem yet, because the instructions did not say to solve for x, it says to find the measures of the angles. So I have to go a little bit further, I wouldn't be done yet. Well remember, one angle was represented by 2x, another was represented by 3x, and the last one was represented by 4x. So let's simply replace x with 20. So then I end up with 2 times 20, which is 40, 3 times 20, which is 60, and 4 times 20, which is 80. So that would be the three, the measures of my three angles. We should double check to make sure we solved it correctly. Hopefully you can see that if you added these three up, it should equal 180. So does 40 plus 60 plus 80 equal 180? It sure does, 40 plus 60 is 100, 100 plus 80 is 180. So 40, 60, and 80 degrees will be the measures of our angles. Be sure you don't say your answer is x equals 20, because it's true, x does equal 20, but you didn't answer the question that was being asked. Make sure you answer the right question.