###
Circumference

Distance around circle

###
Diameter

A chord that passes through the center of the circle

###
Radius

Segment that has one endpoint at the center and the other point on the circle

###
Circle

The set of all points in a plane that are the same distance apart

###
Alternate interior angles

Non-adjecent interior angles that lie on the same side of the transversal

###
Corresponding angles

lie on the same side of the transversal and are in corresponding positions

###
Plane

flat surface with no thickness that contains many lines and extends without end in the direction of all its lines

ABCD

###
Point

location in space with no size

###
Line

series of points that extends in opposite directions with no end

<-> <->

AB BA

###
Line segment

Part of a line with 2 endpoints

___ ___

PQ QP

###
Ray

Part of a line that has exactly one endpoint

<->

CR

###
Parallel

Two lines that lie in the same plane and dont intersect

###
Skew

Lines that are in the same plane and dont intersect and aren't parallel

###
Acute

less than 90º angle

###
Obtuse

Greater than 90º and less than 180º

###
Straight angle

equal to 180º

straight line

###
Adjacent

Share and vertex and a side but no common points

###
Vertical

formed by two intersecting lines and are opposite

###
Congruent

Angles that have the same measure

###
Supplementary

sum of two angles is 180º

###
Complementary

sum of two angles is 90º

###
Transversal

Lines that intersect two other lines in different points

###
Corresponding

Lie on the same side of the transversal and corresponding

###
Polygon

closed plane figure with at least three sides that only meet at their endpoint

###
Triangle

three sided polygon

###
Acute triangle

3 acute angles

###
Right triangle

1 right angle

###
Obtuse triangle

1 obtuse angle

###
Equilateral

3 congruent sides

###
Isosceles triangle

2 congruent sides

###
Scalene triangle

no congruent sides

###
Trapezoid

At least one pair of parallel sides

###
Paralellogram

both pairs of opposite sides are parallel

###
Rhombus

four congruent sides

###
Rectangle

four 90º angles

###
square

four 90º angles and four congruent sides

###
Regular polygon

all sides and angles congruent

###
Chord

segment whose endpoints are in a circle

###
formula for circumference

c=πd

c=πr2

c=circumference

d=diameter

2=2x

π=pi

###
Central angle

angle whose vertex is the center of a circle

360º in a circle

###
Perpendicular lines

lines, segments, or rays that intersect to form right angles

###
segment bisector

lines, segments, or rays that divides a segment into two congruent segments

###
perpendicular bisector

lines, segments, or rays that is perpendicular to the segment in bisects

###
Angle bisector

ray that divides an angle into two congruent angles

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