Geometry / Unit 3: Parallel and Perpendicular Lines
3.2 Angles Formed by a Transversal
Notes
A transversal is a line that crosses two or more lines. It forms eight angles with special names.
- Corresponding angles: same position at each intersection (both upper right, for example).
- Alternate interior angles: between the two lines, on opposite sides of the transversal.
- Alternate exterior angles: outside the two lines, on opposite sides of the transversal.
- Same-side (consecutive) interior angles: between the two lines, on the same side of the transversal.
Practice
Two angles lie between two lines and on opposite sides of a transversal. What are they called?
Interior means between the lines; alternate means opposite sides.
A transversal crosses lines $a$ and $b$. One angle is above line $a$ and right of the transversal. Which angle is corresponding to it?
Corresponding angles are in the same position at each intersection.
Two angles are both between the two lines and on the same side of the transversal. They are:
Same side and interior give same-side interior angles.
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