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 that match

alternate interior angles

angles inbetween the 2 parallel lines

acute angle

less than 90 degrees

right angle

90 degrees

obtuse angle

more than 90 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

segment from triangles vertex midpoint of the opposite side and makes a right angle