What are the conditions for triangle similarity? 1. The triangle obtained by cutting the other two sides (or its extension line) with a straight line parallel to one side of the triangle is similar to the original triangle, which is called parallel similarity for short. 2. Two triangles with equal angles are similar. 3. Two triangles with proportional sides and equal included angles are similar. 4. Two triangles with three proportional sides are similar. (There are also special ones for right-angled triangles; The hypotenuse and the right-angled side are equal to the ratio of two right-angled triangles. What's the conclusion? , 1, and the angles of similar triangles are equal respectively. 2. The sides of similar triangles are respectively proportional. 3. The ratio of bisectors of corresponding angles in similar triangles is equal to the similarity ratio (that is, the ratio of corresponding edges). 4. The ratio of the corresponding midline in similar triangles is equal to the similarity ratio (that is, the ratio of the corresponding sides). 5. The ratio of corresponding heights in similar triangles is equal to the similarity ratio (that is, the ratio of similar triangles perimeter is equal to the similarity ratio (.