Two triangles with equal triangles and proportional sides are called similar triangles. Similar triangles is one of the important proof models in geometry, and it is a generalization of congruent triangles. Congruent triangles can be understood as similar triangles with a similarity ratio of 1.

Similar triangles is actually a set of theorems, which mainly describes the relationship between edges and angles in two triangles in similar triangles geometry.

△ABC is similar to△ def and can be written as △ABC∽△DEF.

Extended data:

The nature of similar triangles

(1) similar triangles have equal angles.

(2) The corresponding sides of similar triangles are proportional.

(3) The ratio of the corresponding high line, the ratio of the corresponding middle line and the ratio of the corresponding angular bisector in the similar triangles are all equal to the similarity ratio.

(4) The perimeter ratio of similar triangles is equal to the similarity ratio.

(5) The area ratio of similar triangles is equal to the square of the similarity ratio.

References:

Baidu Encyclopedia-Judgment Theorem of Similar Triangle