AB and AD - similar triangles - either you could find the ratio between corresponding sides are going to be the same on similar triangles or you could find the ratio between two sides of a similar triangle and compare them to the ratio of the same two corresponding sides on the other similar triangle and they should be the same so by similar triangles we know that the ratio of AB and this by the way - was by angle - angle similarity wanna right that down so now that we know that they're similar we know that the ratio of AB to AD is going to be equal to and we could even look here for the corresponding sides the ratio of AB the corresponding side is gonna be CF its going to equal CF over AD - AD is the same thing as CD - over CD and so we know that the ratio of