This key facts covers Key Facts within Perimeter for GCSE Mathematics. Revise Perimeter in Geometry & Measures for GCSE Mathematics with 10 exam-style questions and 2 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 2 of 4 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 2 of 4
Practice
10 questions
Recall
2 flashcards
Key Facts
| Perimeter | Total distance around the outside of a shape |
| Rectangle | P = 2(l + w) or 2l + 2w |
| Square | P = 4s (4 × side) |
| Triangle | P = a + b + c (add all 3 sides) |
| Circle | Circumference = πd = 2πr |
| Units | Linear units (cm, m, km) - NOT squared! |