Geometry
Plane and solid geometry built on proof: lines and angles, congruent and similar triangles, right-triangle trigonometry, quadrilaterals and polygons, circles, area, surface area and volume, transformations, coordinate geometry, and compass-and-straightedge constructions, every result reasoned from first principles.
0 of 61 lessons available so far.
1. Foundations of Geometry
- Points, Lines, and Planes coming soon
- Segments, Length, and Distance coming soon
- Angles and Their Measure coming soon
- Introduction to Proof coming soon
2. Angles and Parallel Lines
- Complementary, Supplementary, and Vertical Angles coming soon
- Parallel Lines and Transversals coming soon
- Angles in a Triangle coming soon
- The Exterior Angle Theorem coming soon
3. Congruent Triangles
- Triangle Congruence and SSS coming soon
- SAS and ASA Congruence coming soon
- AAS and HL Congruence coming soon
- Isosceles and Equilateral Triangles coming soon
- Using Congruence (CPCTC) coming soon
4. Similar Triangles
- Ratio, Proportion, and Similarity coming soon
- AA Similarity coming soon
- SAS and SSS Similarity coming soon
- Applications of Similarity coming soon
5. Right Triangles and Trigonometry
- The Pythagorean Theorem coming soon
- Special Right Triangles coming soon
- Pythagorean Triples coming soon
- Right-Triangle Trigonometry coming soon
- The Law of Sines and Cosines coming soon
6. Special Segments in Triangles
- Perpendicular Bisectors and the Circumcenter coming soon
- Angle Bisectors and the Incenter coming soon
- Medians and the Centroid coming soon
- Altitudes and the Orthocenter coming soon
7. Quadrilaterals and Polygons
- Parallelograms coming soon
- Rectangles, Rhombi, and Squares coming soon
- Trapezoids and Kites coming soon
- Angles in Polygons coming soon
- Classifying Polygons coming soon
8. Perimeter and Area
- Area of Triangles coming soon
- Area of Quadrilaterals coming soon
- Area of Regular Polygons coming soon
- Same Base, Same Height coming soon
9. Circles
- Circumference and Arc Length coming soon
- Area of Circles and Sectors coming soon
- Inscribed Angles coming soon
- Angles Inside and Outside Circles coming soon
- Tangents, Secants, and Chords coming soon
- Power of a Point coming soon
10. Geometric Inequalities
- The Triangle Inequality coming soon
- Sides and Angles of a Triangle coming soon
- The Hinge Theorem coming soon
11. Solid Geometry
- Prisms and Cylinders coming soon
- Pyramids and Cones coming soon
- Spheres coming soon
- Surface Area and Volume coming soon
12. Transformations
- Translations coming soon
- Reflections coming soon
- Rotations coming soon
- Dilations and Scaling coming soon
- Symmetry coming soon
13. Analytic Geometry
- The Coordinate Plane coming soon
- Distance and Midpoint Formulas coming soon
- Equations of Lines coming soon
- Equations of Circles coming soon
- Coordinate Proofs coming soon
14. Constructions
- Basic Compass and Straightedge Constructions coming soon
- Constructing Bisectors coming soon
- Constructing Regular Polygons coming soon