
To learn over 100 geometry terms, view GradeA's geometry glossary. 
Need help remembering all of this? Try this geometry formula sheet. 



Foundational Geometry Topics 


The Three Undefined Terms in Geometry  Learn the about the building blocks of all geometry. Without these, everything else will be much more difficult! 


Three Basic Geometry Vocabulary Terms  the Segment, the ray, and the angle. Learn these very important starting blocks for geometry, but make sure you know the undefined terms first. 

The Math Pie Symbol  Pi  Curious how pie is a part of math? Take a look at our page on the famous Greek letter pi. 



Beginning Free Geometry Help Topics 

The Pythagorean Theorem  Perhaps the most famous of all the geometry topics. Do not miss GradeA's unique explanation. 

The Segment Addition Postulate  Learn the Segment Addition Postulate by breaking sticks. This activity really helps give the postulate meaning. 

Learn How To Measure Angles  An interesting lesson that uses the hands of a clock to demonstrate the different sizes of angles. 

Learn about Geometry and Triangles  Triangles are categorized by angles and by side lengths. Definitions for acute, right, obtuse, scalene, isosceles, equilateral and equiangular are all given! 

Parallel Lines: Learn about parallel lines, transversals, and all of the special angles that are created, including corresponding angles, alternate interior angles, alternate exterior angles, and sameside interior & exterior angles. 

Special Right Triangles: 454590 & 306090. Learn how to solve for missing sides of these special triangles. 



Formulas 

Geometry Formulas  A series of important formulas that you will need to know for success in geometry. Topics include, area, coordinate geometry, and right triangles. 


To download a comprehensive geometry formula sheet, please view these geometry formulas. 
Circle Formulas View the Video 
Eulers Formula: Relates the faces, edges, and vertices of polyhedron. 

Additional Free Geometry Help Topics 
Transformation Geometry  Learn about translation, reflections and rotations. 
Tangent  Learn the basic definition of a tangent line 
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