This introduction covers The Transversal Detective within Angles in Parallel Lines for GCSE Mathematics. Revise Angles in Parallel Lines 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.
The Transversal Detective
When a line crosses two parallel lines (called a transversal), it creates 8 angles. But here's the magic: there are only really 2 different angle sizes! Once you know one angle, you can work out all the others using three simple rules.
Visual: Angles in Parallel Lines
Practice questions for Angles in Parallel Lines
Two parallel lines are cut by a transversal. Which statement about alternate angles is correct?
State the THREE angle rules that apply when a transversal crosses two parallel lines. For each rule, state whether the angles are equal or supplementary.
Quick recall flashcards
Alternate Angles
Z-shape on parallel lines, equal
Co-interior Angles
C-shape on parallel lines, add to 180°