Basic Geometry terms
pyramid
a 3-dimensional shape whose base is a polygon and whose triangular faces meet at a single point
transformation
a change in size, shape, of position of a geometric figure
polygon
a closed plane figure made of line segments
quadrilateral
a four-sided polygon
vertical angles
a pair of opposite congruent angles formed by two intersecting lines
rhombus
a parallellogram whose four sides are congruent and whose opposite angles are congruent
regular polygon
a polygon in which all sides are the same length and all angles have the same measure
prism
a polyhedron with two parallel, congruent bases; all other faces of the prism are parallelograms
parallelogram
a quadrilateral with opposite sides parallel and congruent
line
a straight path that extends infinitely in opposite directions
sphere
a three-dimensional shape with all points on the surface equidistant from the center
rotation
a transformation of a figure by turning it about a fixed point called the center of rotation or axis
translation
a transformation that moves a geometric figure by sliding each of the points the same distance in the same direction
reflection
a transformation that produces a mirror image of a geometric figure (flip)
acute triangle
a triangle whose interior angles are all acute
scalene triangle
a triangle with no congruent sides
obtuse triangle
a triangle with one obtuse angle
right triangle
a triangle with one right angle
equilateral triangle
a triangle with three congruent sides
isosceles triangle
a triangle with two congruent sides
line symmetry
a type of symmetry in which a line divides a figure into two congruent parts that are mirror images
straight angle
an angle whose measure is 180 degrees
right angle
an angle with a measure of 90 degrees
obtuse angle
an angle with a measure of more than 90 degrees but less than 180 degrees
interior angles
angles on the inner sides of two lines that cut by a transversal
exterior angles
angles on the outer sides of two lines cut by a transversal
acute angles
angles that measures greater than 0 degrees and less than 90 degrees
congruent
having the same size and shape
hypotenuse
in a right triangle, the side opposite the right angle
perpendicular lines
lines that intersect at one point and form right angles
ray
part of a line that has one endpoint and extends forever in the other direction
line segment
part of a line with two endpoints
complementary angles
two angles whose measures have a sum of 90 degrees
supplementary angles
two angles whose sum equals 180 degrees
parallell lines
two lines in the same plane that never intersect
intersecting lines
two lines that cross at exactly one point
