Geometry Vocab

vertex

point of a shape where 2 points meet

area

space inside of a 2d fig

perimeter

distance around a 2d fig

Quadrilateral

a closed fig with 4 sides

parallel

lines that never touch

perpendicular

2 lines that touch at a 90 degree angle

reciprocal

numerator and denominator swap

inverse

reverse operation

function

for every input there is one unique output

congruent

same shape and size

similarity

fig with same shape but different sizes

LoS

line through fig splitting into 2 mirroring parts

transformation

change in image, shape,size,orientation, or location

orientation

rotation around a point

ridgid transformation

size doesn’t change

reflection

fig is flipped over LoR

translation

fig slides to a new location

rotation

shape spins around a point

dilation

change in size and location

complementary

2 angles added together make a sum of 90 degrees

traversal

a line that crosses 2 other lines

supplementary

2 angles added together that make a sum of 180 degrees

vertical angles

2 angles that share a vertex and are opposite of each other

adjacent

2 lines that touch

corresponding angles

angles that match

alternate interior angles

angles on opposite sides of a traversal

acute angle

less than 90 degrees

right angle

90 degrees

obtuse angle

more than 90 degrees but less than 180 degrees

straight angles

180 degrees

isosceles triangle

triangle with 2 = sides

equilateral triangle

triangle with all = sides

theorem

concept proven to be true with known facts

triangle inequality theorem

sum of 2 sides must be greater than the third

triangle sum theorem

angles of a triangle that add up to 180 degrees

pythagorean theorem

in a right triangle the square of hypothenuse = sum of squared to the other 2 sides

consecutive

back to back

hypothenuse

longest side of a right triangle

radical

inverse operation to exponent

radical symbol

symbol of the radical

index

small # on the upper right indicating the root to take

radicand

number under the radical symbol

acute triangle

all 3 angles are less than 90 degrees

right triangle

one angle is = 90 degrees

obtuse triangle

one angle is greater than 90 degrees

base

number raised to a power

exponent

small number on the upper right of the base

factor

number being multiplied by

similar

figs w/same shape and proportions( of sides)

bisector

line dividing segment or angle into 2 = parts

perpendicular bisector

a line that cuts a triangles side in half forming a 90 degree angle

Axes

x and y axis making up a graph

coordinates

x,y values giving the location of a point

ray

line with a beginning but no end

line

line with no beginning or end

segment

line with a beginning and end

point

exact location on graph represented by a dot

non-ridged transformation

fig that changes in size

terms

variables or numbers in an expression separated by +/-

binomial

expression containing 2 terms

trinomial

expression containing 3 terms

alternate exterior angles

angles on opposite sides of a traversal

consecutive interior

angles on the same side of traversal between 2 lines

polynomial

expression containing more than 1 term

corresponding

matching the same position

LoR

line a figure flips over forming a mirrored image

center of dilation

point from which dilation occurs

point of rotation

point a figure spins around

location

the place a point or fig is on the graph

included angle

angle located between 2 sides on a fig

included side

side located between 2 angles

Orgin

Point at the center of a circle

Diameter

Chord that passes through the orgin from one end of a circle to the other

radius

line passes through orgin to one end of a circle

chord

segment that goes from one end of a circle to another

Arc

part of circles circumference

Major Arc

Arc with central angle greater than 180 degrees

Minor Arc

Arc with central angle less than 180 degrees

Central Angle

formed by 2 radii and a vertex at the origin

Degree

measure of angles within the 360 units of a circle

Radian

Unit measurement for angles

Sector

Part of a circle enclosed by 2 radii and an arc

Circumference

Perimeter for circles

Theta

Symbol used to represent an unknown angle

Cosine

in a right triangle, trig function = ratio of the adjacent side over the hypothenuse

Tangent Function

in a right triangle, trig function = ratio of opposite side over the adjacent side

Sine

in a right triangle;e, trig function = ratio of opposite side over the hypothenuse

Tangent

line touching circle at only 1 point and is perpendicular to the radius

Cosecant

reciprocal of sine

Secant

reciprocal of cosine

Cotangent

reciprocal of tangent

Arcsin

inverse function of sine

Arccos

inverse function of cosine

Arctan

inverse function of tangent

opposite side

in a triangle, side opp theta

adjacent side

in a triangle, side touching theta

Apex

vertex at the highest point

Polygon

closed fig w/ 3 or more angles

Apothem

perpendicular distance from the center of polygon to a side

prism

2 parallel, congruent polygon bases and rectangular sides