point
an exact location
line
straight line that continues on forever in both directions
line segment
part of a line connecting two points;it has definite end points
ray
a line that continues on forever in one direction; it has a vertex at one end
parallel lines
two lines on a plane that never meet; they are always the same distance apart
perpendicular lines
lines that cross to form right angles
intersecting lines
when two lines cross each; can form any kind of angle
line of symmetry
imaginary line where you could fold the image and have both halves match exactly
congruent
same size; same shape
acute angle
an angle that measures less than ninety degrees but more than zero degrees
right angle
an angle that measures exactly ninety degrees
obtuse angle
an angle that measures more than 90 degrees but less than 180 degrees
vertex
a common end point
degree
unit of measurement for angles
360 degrees make a circle
protractor
a tool used to measure angles
adjacent angle
two angles are Adjacent when they have a common side and a common vertex; they don't overlap
angle
The amount of turn between two straight lines that have a common end point
right triangle
a triangle that has a right angle
obtuse triangle
a triangle that has an angle greater than 90�
acute triangle
a triangle that has all angles less than 90�
polygon
a closed figure having three or more straight sides
quadrilateral
any four sided polygon
rectangle
quadrilateral where all angles are right angles; opposite sides are parallel; all sides are NOT the same length
square
quadrilateral where all angles are right angles, opposite sides are parallel; all sids are the same length
rhombus
a quadrilateral with four equal sides; forms acute and obtuse angles; all sides are the same length
parallelogram
a quadrilateral with four sides; opposite sides are parallel and equal in length; opposite angles are equal
trapezoid
a quadrilateral with only two parallel sides
pentagon
any polygon with five sides
hexagon
any polygon with six sides
octagon
any polygon with eight sides