# Geometry Vocab Words

Collinear

points lying in the same straight line

Compass

an instrument with two arms, one sharp and one with a pencil that can be used to draw circles

Congruent Segment

segments that have the same length

Coplanar

lines/points in the same plane

Diagonal

a straight line joining two opposite corners of a square

Equidistant/Equidistance

lines/points the same distance from each other

Integers

a whole number

Intersection of a Line

two or more lines crossing each other

Intersection of a Plane

planes that cross through each other

Line

a straight one dimensional figure that extends in both directions

Line Segment

a pat of a line that has a specific length

Linear

consisting of lines

Magnitude

a number's difference from zero

Metric System

the measuring system based on the meter, liter, and gram as units of length, capacity, and weight or mass

Midpoint

the halfway point; the middle of

Natural Number

whole numbers and zero

Non-Coplanar

not occupying the same surface or linear plane

Number Line

a line which numbers are marked at intervals

Perfect Square

the product of a rational number multiplied by itself

Plane (Geometric)

a surface comprising all the straight lines that join any two points lying on it

Point

an exact position or location on a plane surface

Point of Origin

(0,0); where the x-axis and the y-axis intercept

Protractor

an instrument used in measuring or drawing angles

Rational Numbers

can be made by dividing an integer by an integer

Ray

a half-infinite line

Ruler

a tool used to measure straight lines and measure distances

Segment

part of a line or curve

Square Root

a number multiplied by itself

Tolerance

the amount a value can change and still acceptable

U.S. Standard System

units of measurement commonly used in USA

Vector

an object that has both a magnitude and a direction

Vertex

the highest point

Acute Angles

angles that measure less than 90 degrees

Alternate Angles

a pair of angles with different vertices and on opposite sides of a transversal at its intersection with two other lines

Angles

the amount of turn between two lines around their common point

Angle Bisector

a line that splits an angle into two equal angles

Complementary Angle

two angles that add up to 90 degrees

Concave

curved inwards

Congruent Angle

two or more angles that are identical to each other

Congruent Segments

segments that have the same length

Degree

a measure for angles

Isometry

a mapping of a space onto another or onto itself so the distance between any two points in the original space is the same as the distance between their images in the second space

Linear Pairs of Angles

when two lines intersect each other at a single point

Obtuse Angles

an angle that is more then 90 degrees but less than 180 degrees

Opposite Rays

rays that have the same starting point and extend in opposite directions

Parallel Lines

lines on a plane that never meet

Perpendicular Segment Bisector

a line that intersects another line segment perpendicularly and divides it into two parts of equal measurement

Perpendicular Lines

two lines that intersect each other at right angles

Perpendicular Planes

two planes are at right angles

Right Angles

the angle bounded by two lines perpendicular to each other (90 degrees)

Reflex Angles

an angle that is more than 180 degrees and less than 360 degrees

Supplementary Angles

two angles whose sun equal 180

Symmetry

when two or more parts are identical after a flip, slide or turn

Transversals

a line that crosses at least two other lines

Vertical Angles

the angles opposite each other when two lines cross; they are always equal