Basic Geometry

Point

A point is a specific location found in space. It is usually labeled as a letter.

Line Segment

A collection of an infinite number of points that only exist from a certain point to another point.

Ray

A collection of an infinite number of points that start from a point and go the other way infinitely.

Line

A collection of an infinite number of points that extend in both directions infinitely.

Plane

A collection of points along a flat surface which extends in all directions.

Acute

Less than 90 degrees

Right

Equal to 90 degrees

Obtuse

Between 90 and 180 degrees

Straight

Equal to 180 degrees

Reflex

Between 180 and 360 degrees

Revolution

Equal to 360 degrees

Complementary

Angles whose measures add up to 90 degrees

Supplementary

Angles whose measures add up to 180 degrees

Congruent

Angles with equal measurement

Adjacent

Angles that are beside each other

Vertical

Angles that are opposite each other; congruent

Corresponding

Angles that are in the same position; congruent

Alternate Interior

Angles that are on opposite sides of the transversal, but are closer to the center of the figure; congruent

Alternate Exterior

Angles that are on opposite sides of the transversal, but are farther from the center of the figure; congruent

Same-Side Interior

Angles that are on the same side of the transversal, but are closer to the center of the figure; equal 180

Same-Side Exterior

Angles that are on the same side of the transversal, but are farther from the center of the figure; equal 180

Convex

All exterior angles are not acute

Concave

At least one exterior angle is acute

Undeca

11

Dodeca

12