63 terms

Geometry

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point
a definite location in space
line
a series of dots so close together that they appear as one continuous thing; there is no beginning or end to a "line".
ray
a part of a line that extends indefinitely from one direction
line segment
two endpoints and the straight path between them; a "line" with a beginning and an ending.
intersecting lines
two or more lines that meet and cross at any angle.
perpendicular lines
lines that intersect at a right angle
parallel lines
lines going in the same direction without touching; two lines (or line segments) with the same slope that are always the same distance apart.
line of symmetry
a line that divides a figure into two halves that reflect each other
congruent figures
figures that are the same size and shape
vertical
line going up and down
horizontal
lines going side to side
plane
is a flat two-dimensional surface that is unending in all directions
angle
two rays with a common endpoint
right angle
an angle that measures 90 degrees
acute angle
an angle with a measure greater than 0 degrees and less than 90 degrees
obtuse angle
an angle that measures greater than 90 degrees and less than 180 degrees
reflex angle
angle that measures more than 180 degrees and less than 360 degrees
complementary angle
if the sum of two angles measures 90 degrees
supplementary angle
if the sum of two angles measure 180 degrees
straight angle
180 degree angle
polygon
a closed figure with three or more straight sides
circumference
the distance around the edge of a circle
right triangle
a triangle with one right angle
acute triangle
triangle whose interior angles are all acute
obtuse triangle
triangle that has one angle more than 90 degrees
equilateral triangle
a triangle with three congruent sides
isosceles triangle
a triangle with two equal sides, the two base angles are also equal
scalene triangle
all sides are different
measure of the interior angles of a triangle
180 degrees
faces
the flat surfaces of a 3-D figure
edges
the intersection of faces of a 3-D figure
square
a parallelogram with all sides congruent and all angles congruent
rectangle
a quadrilateral with four right angles; opposite sides are parallel and congruent
trapezoid
a quadrilateral having two sides parallel
rhombus
a parallelogram with four equal sides
parallelogram
a quadrilateral that has both pairs of opposite sides parallel
circle
the set of all points in a plane that are the same distance from a given point
radius
the distance from the center of the circle to any given point on the circle
diameter
the distance across the circle through the center
circumference
the distance around a circle
area
the number of the square units in a figure
perimeter
the distance around any closed figure
volume
the amount of space a 3-D figure containes; the number of cubic units in a 3-D figure.
quadrilateral
a polygon with four sides
pentagon
a polygon with five sides
hexagon
a polygon with six sides
heptagon
a polygon with seven sides
octagon
a polygon with eight sides
nonagon
a polygon with nine sides
decagon
a polygon with ten sides
solid
a three-dimensional (3-D) figure
base
the bottom side of a geometric figure from which the altitude or height can be constructed
dodecagon
a 12 sided polygon
equilateral
means that all sides are equal
sum
the answer to an addition problem
difference
the answer to a subtraction problem
product
the answer to a multiplication problem
quotient
the answer to a division problem
sum of the interior angles of a polygon
(n-2)180 ; with n as the number of sides in the figure
rhombus
has four equal sides
adjacent angles
angles that share a vertex and a side but have no interior points in common
vertical angles
angles that are opposite from each other; formed from two intersecting lines
height of a figure
the perpendicular distance from the base to the opposite side of the figure (always forms a right angle with the base); also called the altitude