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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

Right angle

90º angle

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

Quadrilateral

4 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

Pentagon

5

Heptagon

7

Decagon

10

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

pi

3.1415....etc
π

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