Euclidean Geometry Terms

1

2

3

4

Obtuse

Complimentary

Supplementary

Right

A point is an "undefined" term

Isosceles triangles have no sides congruent

A line needs two points in order to be named correctly

Supplementary angles sum to 180 degrees

Parallel lines

Intersecting lines

Right lines

Perpendicular lines

Line Segments are two-dimensional, Lines are one-dimensional

Lines can be represented on single planes; Line Segments can only be represented on multiple planes.

Line Segments have finite lengths; Lines go on forever.

Line segments are geometric figures; Lines are not.

Line

Line segment

Ray

Angle

Line Segment

Line

Ray

Point

Postulates do not require a proof and are presumed true, while theorems are statements requiring proof.

Postulates are statements that require proof, while theorems cannot be proven.

Both postulates and theorems do not require proof and are assumed to be true.

There is no difference between postulates and theorems.

D, E, B

C, B, A

M, E, C

A, F, E

line a

R

line KL

line HK

Point J

Line HK

Point K

Line MN

Accurate

Line-up

Collinear

Sightline

Ray

Point

Line

Line segment

Any 2 points on the line, or a lowercase script letter.

Any 3 points on the line.

Any 1 point on the line.

Any 3 points on the line, or a uppercase script letter.

right

acute

obtuse

straight

acute

obtuse

right

straight

An angle that measures more than 90 degrees.

An angle that measures less than 90 degrees.

An angle that measures exactly 90 degrees.

An angle that measures exactly 180 degrees. 

Angles that add up to 180°

Angles that add up to 90°

Angles that are equal to each other

Angles that are opposite of each other when lines intersect

Angles that add up to 180°

Angles that add up to 90°

Angles that are equal to each other

Angles that are opposite of each other when lines intersect.