Proving Triangles Similar
This page introduces three key concepts for proving triangle similarity: the Angle-Angle AA Similarity Postulate, the Side-Angle-Side SAS Similarity Theorem, and the Side-Side-Side SSS Similarity Theorem.
The AA Similarity Postulate states that if two angles of one triangle are congruent to two angles of another triangle, then the triangles are similar. This is a fundamental concept in proving triangle similarity theorems.
Definition: Triangle similarity means that two triangles have the same shape but may differ in size.
The SAS Similarity Theorem provides another method for proving triangle similarity. It states that if an angle of one triangle is congruent to an angle of a second triangle, and the sides that include these angles are proportional, then the triangles are similar.
Example: In the SAS triangle similarity theorem, if AB/QR = AC/QS and ∠A ≅ ∠Q, then ΔABC ~ ΔQRS.
The SSS Similarity Theorem offers a third way to prove triangle similarity. This theorem states that if the corresponding sides of two triangles are proportional, then the triangles are similar.
Highlight: The SSS Similarity Theorem is particularly useful when dealing with problems where only side lengths are known.
These theorems provide powerful tools for solving various geometry problems involving similar triangles. They are essential for students learning how to prove triangle similarity and for solving more complex geometric problems.