Basic Principles of Geometry

Interested in learning about geometry? This beginner math lesson introduces the basic building blocks of geometry, like lines, angles, and points.

Now that you know the basic building blocks of geometry—such as lines, rays, and angles—learn how to draw and denote them properly in this beginner math lesson.

Did you know there could be eight triangles within one quadrilateral figure? In this lesson, learn how to identify and denote angles within geometric figures.

Ready to start denoting more challenging angles? In this beginner geometry lesson, practice naming angle vertices and sides, and learn about straight angles.

Need help understanding unions and intersections in your geometry homework? This lesson from Math Fortress walks through practice questions for new students.

What happens when you come across a geometry problem with multiple sets? This lesson shows you how to find more unions and intersections for multiple sets.

In this final lesson of the introductory geometry course from Math Fortress, practice identifying unions and intersections of lines and angles.

In this basic geometry lesson, learn about the concepts associated with segment measurement, including measuring segments and congruent segments.

In this basic geometry lesson, practice what you've learned about measuring segments and congruence by running through eight example problems.

In this basic geometry lesson, learn about the concepts associated with congruent segments, including identifying congruent segments within diagrams.

In this last lesson on measurement of segments, review two challenging geometry problems involving congruent segments and algebra.

In this lesson, review how to name and denote angles by their vertex or sides, and find out how to measure angles with a protractor and denote them properly.

Now that you’ve reviewed angle terminology and practiced measuring them, find out how to classify angles according to size in this lesson from Math Fortress.

Review the parts of a degree, learn how to denote measurements clearly, and understand the definition of congruent angles and how to denote congruence.

In this lesson, review examples and exercises on measuring angles. This is a chance to follow keep the geometric concepts you’ve just learned active.

Build on your geometry knowledge with more challenging exercises on the parts of a degree. Math Fortress explains the complexities of this basic concept.

Get more practice measuring angles. Begin by measuring the degrees between clock hands, then practice determining measurements based on given congruent angles.

Challenge yourself further with exercises in which students determine an angle’s measurement by first solving for X in algebraic expressions.

This lesson from Math Fortress includes basic to intermediate geometry problems in which students measure angles through algebraic expressions and inequalities.

In this final lesson on measurement of angles, follow along as Math Fortress solves two challenging geometry problems that require the use of algebra.

This lesson introduces the mathematical concept of collinearity. Understand the definition of collinearity and learn about how it applies to geometry.

In this lesson, follow along to five examples that illustrate how to use the math concepts of collinearity and betweenness of points in various applications.

In this lesson, follow along and solve three slightly more challenging examples illustrating how to use the concepts of collinearity and triangle inequality.

In this final lesson, follow along to solve four example problems that involve angle measurements. Use information from diagrams to solve these problems.

This lesson explains the basics of how to write two-column algebraic and geometric proofs. It also covers the elements of an axiomatic system. Let's dig in!

In this lesson, Math Fortress presents and proves two basic theorems in geometry, the right angles theorem and the straight angles theorem.

Follow along to three examples that illustrate how to use previously proven theorems, assumptions, and properties in order to write a geometric proof.

Learn how to identify midpoints, bisectors of segments, trisection points, trisectors of segments, adjacent angles, angle bisectors, and angle trisectors.

In this lesson, continue building basic geometry skills by completing six proofs that explore the division of segments and angles as covered in lesson one.

In this lesson, continue building basic geometry skills by reviewing nine different examples that demonstrate the division of segments and related concepts.

Continue building your understanding of midpoints, bisectors, and trisectors by completing five geometric proofs that explore these basic concepts.

Continue building your understanding of midpoints and bisectors, with some more challenging geometric proofs that explore these basic geometry concepts.

In this lesson, continue building skills by exploring some example geometry proofs that involve adjacent angles, angle bisectors and angle trisectors.

Continue building skills by exploring three slightly more challenging examples of geometry proofs that involve angle bisectors and angle trisectors.

In this final lesson on division of segments and angles, follow along to complete two challenging proofs involving angle bisectors and angle trisectors.