The second sign of the similarity of a triangle.

Let’s remember the second sign of the similarity of triangles. It can be written in the form of a theorem (as it is presented in the textbook).

The second sign is called “The second sign of the similarity of triangles is the similarity of triangles along two proportional sides and the angle between them.”

The very similarity criterion (the theorem on similar triangles) sounds as follows:

If the two sides of one triangle are proportional to the two sides of the other triangle and the angles formed by these sides are equal, then such triangles are similar.