Lines, Angles & Transversals
Section: GeometryGRE frequency: HighPro
1. Core Idea
Almost every angle-chasing question is solved by repeatedly applying three facts:
- Angles on a straight line add to 180 degrees.
- Angles around a point add to 360 degrees.
- Parallel lines cut by a transversal create only two distinct angle values, and they sum to 180.
That third point is the one to hammer: with parallel lines there are only ever two numbers on the page — call them x and 180 - x.
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