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Polygon

a closed figure with 3 or more line segments

quadrilateral

a polygon with four sides

pentagon

a polygon with five sides

angles

the figure formed by 2 rays with the same endpoint

octagon

a polygon with eight sides

decagon

a polygon with 10 sides

scalene

a shape with no congruent sides

isosceles

a shape with more than 1 congruent sides

equilateral

a polygon with all sides congruent

right

a shape or figure with a 90 degree angle

parallelogram

a quadrilateral whose opposite sides are parallel

rectangle

a parallelogram with four right angles

trapezoid

a quadrilateral with one pair of parallel sides

square

a rectangle which is equilateral

degrees

the basic unit by which angles are measured

vertex

the intersection of the two sides of an angle i

points

a dot that represents a location in a plane or space

line

a straight path of points that extend forever in opposite directions

plane

a flat surface that extends forever in all different directions

ray

part of a line that has 1 endpoint and extends forever in only 1 direction

line segment

part of a line consisting of 2 endpoints and all the points between them

congruent

shapes that are exactly the same

intersection

the set of points that are common to 2 or more lines

parallel

lines in the same place but do not intersect

vertex

the point at the corner with an angle, plane angle, or solid figure

measure

the measure of something (angle)

protractor

to use and approximate the measure of an angle

perpendicular

2 lines that meet at right angles

complementary

2 angles that if the sum of their measure is 90 degrees

supplementary

2 angles and if the sum of their measure is 180 degrees

vertical angles

angles that are formed by intersecting lines (angles across from each other)

corresponding angles

angles that are formed by intersecting lines (horizontal lines that form angles)

skew lines

in 3-D world, lines don't cross but not parallel

scalene triangle

all sides have different lengths

isosceles triangle

at least 2 sides have to be the same

equilateral triangle

all 3 sides have to be the same (60 degrees)

acute triangle

if all 3 angles are acute

obtuse triangle

if 1 of the angles are obtuse

right triangle

if one of the angles is a right angles