###
mixed number

A mixed number is the sum of a whole number and a fraction.

###
intersect

when two lines cross

###
point of intersection

the place where the lines cross

###
parallel lines

if two lines in the same plane do not intersect

###
perpendicular

if two lines make square corners

###
right angles

angles made by perpendicular lines

###
straight angle

two right angles

###
acute angle

an angle smaller than a right angle

###
obtuse angle

an angle smaller than a right angle

###
polygon

the number of sides is always equal to the number of vertices

###
side

each segment of a polygon

###
vertex {plural: vertices}

endpoint of a side

###
concave polygon

if a polygon has a indentation

###
convex polygon

any polygon that does not have an indentation

###
parallelogram

quadrilateral that has two pairs of parallel sides

###
trapezoid

is a quadrilateral that has exactly two parallel sides

###
rhombus

equilateral parallelogram

###
square

rhombus with four right angles

###
perimeter

measure around or distance around

###
radius

distance from the center of the circle

###
diameter

twice the length of the radius

###
circumference

perimeter of a circle

###
circumference of a circle

pi D=pi(2r)=2(pi)r

###
infinte numbers

(1, 3, 5, 7 ....)

###
finite numbers

(1, 3, 4, 6 )

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