Chapter 11 Geometry
triangle
a 3 sides and 3 angles
quadrilateral
a four-sided figure.
parallelogram
a four-sided plane rectilinear figure with opposite sides parallel.
pyramid
a monumental structure with a square or triangular base and sloping sides that meet in a point at the top,
rhombus
a parallelogram with opposite equal acute angles, opposite equal obtuse angles, and four equal sides.
polygon
a plane figure with at least three straight sides and angles, and typically five or more.
octagon
a plane figure with eight straight sides and eight angles.
pentagon
a plane figure with five straight sides and five angles.
square
a plane figure with four equal straight sides and four right angles.
rectangle
a plane figure with four straight sides and four right angles, especially one with unequal adjacent sides, in contrast to a square.
nonagon
a plane figure with nine straight sides and nine angles.
hexagon
a plane figure with six straight sides and angles.
decagon
a plane figure with ten straight sides and angles.
regular polygon
a polygon in which all sides and angles are congrugent
trapezoid
a quadrilateral with only one pair of parallel sides.
sphere
a round solid figure, or its surface, with every point on its surface equidistant from its center.
polyhedrons
a solid figure with faces that are polygons
cylinder
a solid geometric figure with straight parallel sides and a circular or oval cross section.
cone
a solid or hollow object that tapers from a circular or roughly circular base to a point.
acute triangle
a triangle with 2 angles less than 90 degrees
isosceles triangle
a triangle with 2 congrugent sides
equilateral triangle
a triangle with 3 congrugent sides
right triangle
a triangle with a right angle
obtuse triangle
a triangle with one obtuse angle
right angle
an angle that measures 90 degrees
congruent
identical in form; coinciding exactly when superimposed.
Hexagonal prism
the hexagonal prism is a prism with hexagonal base. This polyhedron has 8 faces, 18 edges, and 12 vertices.
angle
the point were lines meet
non-polyhedrons
three dimensional figures with curved faces
rectangular pyramid
. A rectangular pyramid has a rectangle for a base with triangles for the other faces. Sometimes the rectangle at the base is actually a square.
Heptagon
A 7-sided figure
not a regular polygon
A polygon that does not have all sides equal and all angles equal. A polygon is "regular" only when all angles are equal and all sides are equal, otherwise it is irregular
pentagonal prism
A rectangular prism is a solid figure where all sides are rectangles and all sides meet perpendicular.
rectangular prism
A rectangular prism is a solid figure where all sides are rectangles and all sides meet perpendicular.
prism
A solid figure that has two congruent, parallel polygons as its bases. Its sides are parallelograms
triangular pyramid
A triangular pyramid is a pyramid having a triangular base.
acute angle
An angle that is less than 90 degrees
obtuse angle
An angle that measures more than 90 degrees but less than 180 degrees
lateral faces
Any surface of a polyhedron other than a base
base
In 2 dimensions, one side of a triangle or parelellogram
pentagonal pyramid
In geometry, a pentagonal pyramid is a pyramid with a pentagonal base upon which are erected five triangular faces that meet at a point (the vertex). Like any pyramid, it is self-dual. The regular pentagonal pyramid has a base that is a regular pentagon and lateral faces that are equilateral triangles.
hexagonal prism
In geometry, the hexagonal prism is a prism with hexagonal base. This polyhedron has 8 faces, 18 edges, and 12 vertices.
octagonal prism
In geometry, the octagonal prism is the sixth in an infinite set of prisms, formed by square sides and two regular octagon caps. If faces are all regular, it is a semiregular polyhedron.
