Geometry Vocabulary Flashcards

Vocabulary flashcards covering key geometry definitions and angle relationships from the lecture transcript.

Acute angle

An angle that measures greater than $0\,\text{degrees}$ and less than $90\,\text{degrees}$

Adjacent angles

Two angles in the same plane with a common vertex and common side

Alternate exterior angles

For two lines intersected by a transversal a pair of angles that lie on opposite sides of the transversal and outside the other two lines

Alternate interior angles

For two lines intersected by a transversal a pair of nonadjacent angels that lie on opposite sides of the transversal and between the other two lines

Bisect

To divide into two congruent parts

Colinear

Points that lie on the same line

Complementary angles

Two angles whose measure have the sum of $90\,\text{degrees}$

Congruent

Having the same shape and size

Interior angle

An angle formed by two sides of a polygon with a common vertex

Line

An undefined term in geometry, a line is a straight path that has no thickness and extends forever

Line segment

A part of a line consisting of two endpoints and all the points between them

Midpoint

The point that divides a segment into two congruent segments

Obtuse angle

An angle that is greater that $90\,\text{degrees}$ and less than $180\,\text{degrees}$

Parallel lines

Lines in the same plane that do not intersect

Plane

An undefined term in geometry. It is a flat surface that has no thickness and extends forever

Point

A undefined term in geometry, it names a location and has no size

Perpendicular lines

Lines that intersect at a $90\,\text{degree}$ angle

Proof

An argument that uses logic to show that a conclusion is true

Right angle

An angle that measure $90\,\text{degrees}$

Straight angle

An angle that measures $180\,\text{degrees}$

Vertical angles

The non-adjacent angels formed by two intersecting lines

Vertex

An intersection of to two sides of a polygon

Postulate

A statement that is accepted as true without a proof also called an axiom

Theorem

A statement that has been proven

Consecutive exterior angles

For two lines intersected by a transversal, a pair of angles that lie on opposite sides of the transversal and outside two lines

Consecutive interior angles

For two lines intersected by a transversal, a pair of angles that lie on the same side of the transversal and between two lines

Transversal

A line that intersects two coplanar lines at a two different points

Supplementary angles

Two angles whose sum have the measure of $180\,\text{degrees}$

Corresponding angles

For two lines intersected by a transversal, a pair of angles that lie on the same side of the transversal and on the same sides of the other two lines

Symmetry

A figure that when folded in half (any direction) create a mirror image of itself