In Geometry, understanding and mastering the concept of congruent triangles is essential. In this unit, students will learn and review theorems and postulates related to congruent triangles. Homework 7 is focused on proofs, and this article will review all methods used when proving congruent triangles.

## ASA and AAS Theorems

The ASA and AAS theorems provide a way to prove two triangles are congruent. The ASA theorem states that if two angles and the included side of one triangle are congruent to two angles and the included side of another triangle, then the two triangles are congruent. The AAS theorem states that if two angles and a non-included side of one triangle are congruent to two angles and a non-included side of another triangle, then the two triangles are congruent. Both the ASA and AAS theorems must be used in the proof of congruent triangles.

## SAS Theorem

The SAS theorem provides an easier way to prove two triangles are congruent. The SAS theorem states that if two sides and the included angle of one triangle are congruent to two sides and the included angle of another triangle, then the two triangles are congruent. This theorem simplifies the proof as it only requires three pieces of congruence information instead of six.

## HL Theorem

The HL theorem is a more advanced theorem used to prove congruent triangles. The HL theorem states that if two sides and their included angles of one triangle are congruent to two sides and their included angles of another triangle, then the two triangles are congruent. This theorem requires four pieces of congruence information, making it more difficult to use than the SAS theorem.

## Proof by Contradiction

Proof by contradiction is an alternate method used to prove congruent triangles. This method involves assuming the opposite of what you want to prove is true, and then using the properties of congruent triangles to show that the assumption is false. This method can be used to prove two triangles are congruent, or to prove two triangles are not congruent.

The theorems and methods discussed in this article can be used to help students prove congruent triangles in Geometry. Understanding and mastering these concepts is essential for success in Geometry and other math courses. With practice and review of these methods, students will be able to complete Homework 7 and other proofs with ease.