This key facts covers Triangle Angle Rules within Properties of Triangles for GCSE Mathematics. Revise Properties of Triangles in Geometry & Measures for GCSE Mathematics with 12 exam-style questions and 3 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 3 of 8 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 3 of 8
Practice
12 questions
Recall
3 flashcards
Triangle Angle Rules
| Rule | Description |
|---|---|
| Interior angles sum | Always add up to 180° |
| Exterior angle | Equals the sum of the two opposite interior angles |
| Isosceles base angles | The two angles opposite the equal sides are equal |