Geometry Vocabulary

By Stanley Kilgo

Adjacent Angles

Two angles that touch at the same point.

Alternate Exterior Angles

A pair of two angles that are on opposite outside sides of the transversal.

Alternate Interior Angles

A pair of two angles there are on the opposite inside sides of a transversal.

Complementary Angles

Two angles when added up equal 90 degrees.

Corresponding Angles

where two angles on a transversal are equal

Supplementary Angles

two angles that add up to 180

Parallel lines

two lines that don't touch

Perpendicular Lines

Two lines that are 90 degrees to each other

Transversal lines

A line that passes through two parallel lines

Vertical Angles

Angles that are opposite each other.


the outside of a shape


the inside of a shape

Surface area

Area of a single surface


how much a shape can hold


area around a circle


one side of a circle to another


from the outside of a circle to the middle


one side of a 3D object


where two faces meet


Where two edges meet