PrepWisePrepWiseProperties of Triangles
Geometry & MeasuresIntroduction

The 180° Rule

Part of Properties of Triangles · GCSE GCSE Mathematics revision

This introduction covers The 180° Rule 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. Use this page as part of a wider topic revision path rather than treating it as an isolated fact. It is section 1 of 9 in this topic. Use this introduction to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 1 of 9

Practice

12 questions

Recall

3 flashcards

The 180° Rule

Every triangle in the universe has angles that add up to exactly 180°. It doesn't matter if it's tiny or massive, flat or tilted - the three angles ALWAYS sum to 180°. This is the most important triangle fact you'll ever learn!

Visual: Types of Triangles

Diagram showing four triangle types: Equilateral (all sides equal, all angles 60°), Isosceles (2 sides equal, 2 angles equal), Scalene (all sides different), Right-angled (one 90° angle)

Tip: Equal sides have matching tick marks, equal angles have matching arcs

Keep building this topic

Read this section alongside the surrounding pages in Properties of Triangles. That gives you the full topic sequence instead of a single isolated revision point.

Types of TrianglesTriangle Angle RulesWorked Example 1: Finding a Missing Angle

Practice Questions for Properties of Triangles

What is the sum of the interior angles of any triangle?

  • A. 90°
  • B. 180°
  • C. 270°
  • D. 360°
1 markfoundation

Describe the key properties of an equilateral triangle. State two properties relating to sides and two relating to angles.

2 marksstandard

Quick Recall Flashcards

Triangle Angle Sum
Always 180°
Isosceles Triangle
Two equal sides, two equal angles

12 questions on Properties of Triangles — practise free

Instant marking, adaptive difficulty, and 3 spaced repetition flashcards. Free until your GCSEs.

Try PrepWise Free

Back to

Properties of Triangles

Next

Types of Triangles