| M5 Home Page |
| Fact Monster | Triangles |
| Interactive Mathematics | Triangles |
| Interactive Mathematics | Angle Sum of a Triangle |
| Interactive Mathematics | Exterior Angle of a Triangle |
| Math Cove | Triangles |
| Pink Monkey | Triangles |
| Purplemath | Basic Triangle Values |
| Triton College | Triangles |
| Math Reference | Congruent Triangles |
| Wing Kuen | Congruent Triangles |
| CITE | Area of a Triangle |
| CITE | Perimeter of a Triangle |
| Go Math | Triangles - Area and Perimeter |
| Math2.org | Areas, Volumes, and Surface Areas |
| Pink Monkey | Perimeter and Area: Triangle |
| Krell Institute | Right Triangles |
| Math Homework Help | Special Right Triangles |
| Math to Build On | Names of the Sides of a Right Triangle |
| Math to Build On | Right Triangles |
| WebMath | Right Triangles |
| Zona Land | 45-45-90 and 30-60-90 Triangles |
| Harcourt School | Acute Triangle |
| Harcourt School | Equilateral Triangles |
| Harcourt School | Isosceles Triangle |
| Harcourt School | Obtuse Triangle |
| Math Reference | Isosceles and Equilateral Triangles |
| Math to Build On | Isosceles Triangle |
| CITE | Pythagorean Relationship |
| Go Math | Pythagorean Theorem |
| Math Education and Technology | Pythagorean Theorem |
| Math Lair | The Pythagorean Theorem |
| Math to Build On | Length of the Hypotenuse of a Right Triangle |
| Math to Build On | Length of a Leg of a Right Triangle |
| Maths Tutor | Pythagoras's Theorem |
| MathsRevision.net | Pythagoras's Theorem |
| Project GCSE | Pythagoras's Theorem |
| Math Cove | A Picture Proof of the Pythagorean Theorem |
| Wing Kuen | Visual Proof of Pythagoras's Theorem |
| About.com | Pythagorean Theorem Links |
| Curious Math | Pythagoras Triplets |
| Dave Joyce | Similar Triangles and the Pythagorean Theorem |
| Purplemath | The Distance Formula |
| Coolmath | Interior Angles |
| Coolmath | What Does Congruent Mean? |
| Math Education and Technology | Congruent Figures and Triangles |
| Math to Build On | Degrees: Circles, Triangles, Rectangles, Squares |
| Maths Tutor | Areas and Volumes (i) |
| Mrs. Glosser | Lesson on Perimeter of Polygons |
| Purplemath | Geometric Formulae Review |
| RegentsPrep.Org | Vocabulary Resource Sheet for Proofs |
| RegentsPrep.Org | Theorems for Beginning Congruent Triangle Proofs |
| Cut the Knot | Pythagorean Theorem |
| Cut the Knot | Morley's Miracle |
| Howe-Two Software | Altitude, Angle Bisector, and Median |
| Wing Kuen | Exterior Angle of a Triangle |
| Wing Kuen | Mid-point Theorem |
| AAA Math | Area of a Triangle |
| Exeter CIMT | Area of a Triangle |
| MathGuide | Quizmaster: Area of a Triangle |
| RegentsPrep.Org | Recognizing Congruent Triangles |
| Utah State University | Congruent Triangles |
| Exeter CIMT | Constructing Triangles |
| Math Notes | Triangles |
| Math Notes | Similar Triangles |
| Math Notes | Pythagorean Theorem |
| MathGuide | Quizmaster: Finding the Hypotenuse |
| MathGuide | Quizmaster: Finding the Leg |
| Shodor | Triangle Explorer |
| A+ Math | Geometry Flashcards |
| A+ Math | MATHO Geometry Game |
| A+ Math | Geometry Hidden Picture Game |
| AAA Math | Geometry |
| JRW | Areas and Volumes |
| Quia | Geometric Terms |
| Quia | Triangles and Polygons |
| RegentsPrep.Org | Vocabulary Practice |
| RegentsPrep.Org | Practice with Beginning Congruent Triangle Proofs |
| Go Math | Triangles - Area and Perimeter Worksheet |
| SCWeb4Free | Areas of Triangles |