Congruent triangles



Congruent triangles have the same size and the same shape. When triangles are congruent, all corresponding sides and corresponding angles are also congruent or equal

For examples, the two triangles below are congruent

Congruent triangles


Corresponding angles are angles in the same position

Corresponding angles of congruent triangles


Corresponding sides are sides that are in the same position

The two triangles above have a side with 3 markings. These sides are at the same position and thus are corresponding

Congruent sides are sides that have equal measures

Congruent angles are angles that have equal sides and equal measures

In the triangle above, if we pull out the side with one and three markings and the included angle, we get the following:

Congruent angles


The above 48 degrees angle is a good example of congruent angles because the sides are equal and the angles are equal

Included side: A side between two angles

Included angle: An angle between two sides

There are three postulates and two theorems that are used to identify if two triangles are congruent

With these postulates and theorems, you don't have to check if all corresponding angles and all sides are congruent

If the triangles meet the condition of the postulate or theorem, then, you have congruent triangles.

They are the SSS postulate, SAS postulate, ASA postulate, AAS theorem, and Hypotenuse-Leg theorem

SSS postulate:

If three sides of a triangle are congruent to three sides of a second triangle, then the two triangles are congruent

Example:

Congruent triangles BY SSS


ASA postulate:

If two angles and the side between these two angles (included side) of one triangle are congruent to the corresponding angles and the included side of a second triangle, then the two triangles are congruent

Example:

Congruent traingles by ASA


SAS postulate:

If two sides and the angle between these two sides (included angle) of one triangle are congruent to the corresponding two sides and the included angle of a second triangle, then the two triangles are congruent

Example:

Congruent triangles by SAS


AAS theorem:

If two angles and a side not between these two angles of one triangle are congruent to two angles and the corresponding side not between these two angles of a second triangle, then the two triangles are congruent



Example:

Congruent triangle by AAS


Hypotenuse-Leg theorem:

If the hypotenuse and leg of a right triangle are congruent to the hypotenuse and corresponding leg of a second right triangle, then the two triangles are congruent

Example:

Congruent triangle by Hypotenuse-Leg theorem








Recent Articles

  1. Linear Parent Function

    Nov 20, 17 11:18 AM

    What is a linear parent function? Crystal clear explanation.

    Read More

New math lessons

Your email is safe with us. We will only use it to inform you about new math lessons.

            Follow me on Pinterest





Recent Lessons

  1. Linear Parent Function

    Nov 20, 17 11:18 AM

    What is a linear parent function? Crystal clear explanation.

    Read More

  Our Top Pages

Formula for percentage

Compatible numbers

Basic math test

Basic math formulas

Types of angles

Math problem solver

Algebra word problems

Surface area of a cube

Finding the average 

Scale drawings

Tough Algebra Word Problems.

If you can solve these problems with no help, you must be a genius!


Everything you need to prepare for an important exam!

K-12 tests, GED math test, basic math tests, geometry tests, algebra tests. 


Real Life Math Skills

Learn about investing money, budgeting your money, paying taxes, mortgage loans, and even the math involved in playing baseball.

 Recommended

Scientific Notation Quiz

Types of Angles Quiz

Graphing Slope Quiz

Adding and Subtracting Matrices Quiz  

Factoring Trinomials Quiz 

Solving Absolute Value Equations Quiz  

Order of Operations Quiz