Three is to Three

Triangle Classifications

Main Lesson: Triangle Classifications

Learn how to classify triangles by the lengths of their sides and the measures of their angles.

Angle Properties of Triangles

Main Lesson: Angle Properties of Triangles

Connect your knowledge of angles to triangles and get introduced to significant theorems including the Triangle Angle Sum Theorem and the Exterior Angle Theorem.

Congruent Triangles

Main Lesson: Congruent Triangles

With the help of CPCTC and the Third Angles Theorem, learn how to prove that triangles are congruent.

Triangle Congruence - SSS and SAS

Main Lesson: Triangle Congruence - SSS and SAS

Introduction of two postulates that will help us prove congruence between triangles: the SSS Postulate (Side-Side-Side) and the SAS Postulate (Side-Angle-Side).

Triangle Congruence - ASA and AAS

Main Lesson: Triangle Congruence - ASA and AAS

Learn how to use the ASA Postulate (Angle-Side-Angle) and AAS Postulate (Angle-Angle-Side) to help us prove that triangles are congruent.

Properties of Isosceles and Equilateral Triangles

Main Lesson: Properties of Isosceles and Equilateral Triangles

Discover key characteristics of isosceles and equilateral triangles and work your way through five helpful exercises.

Right Triangle Congruence

Main Lesson: Right Triangle Congruence

We've learned about the congruence postulates of any triangles. Now, let's learn about those that apply specifically to right triangles.

Bisectors of Triangles

Main Lesson: Bisectors of Triangles

Take a look at perpendicular bisectors and angle bisectors, as well as how to use them for geometric computations.

Inequalities and Relationships Within a Triangle

Main Lesson: Inequalities and Relationships Within a Triangle

Learn about the different inequalities within a triangle, including the Triangle Inequality Theorem. Also, take a look at some helpful angle-side relationships of triangles.

Area and Perimeter of a Triangle