How can we help?

You can also find more resources in our Help Center.

polyhedron

a solid figure with many sides, such as a pyramid

face

a surface forming part of the outside of an object

edge

a sharp side formed by the intersection of two surfaces of an object

vertex

the point of intersection of lines or the point opposite the base of a figure

regular polyhedron

any one of five solids whose faces are congruent regular polygons and whose polyhedral angles are all congruent

convex

curving or bulging outward

cross section

a section created by a plane cutting a solid perpendicular to its longest axis

platonic solids

tetrahedron, cube, regular octahedron, regular dodecahedron, regular icosahedron

tetrahedron

any polyhedron having four plane faces

octahedron

any polyhedron having eight plane faces

dodecahedron

any polyhedron having twelve plane faces

icosahedron

any polyhedron having twenty plane faces

prism

a polyhedron with two congruent and parallel faces (the bases) and whose lateral faces are parallelograms

bases

polygons that make up the bottoms of a polyhedron

lateral faces

the faces that are not the base of a parallelogram

right prism

each lateral edge is perpendicular to both bases

oblique prism

a prism that is not a right prism

surface area of a polyhedron

the sum of the areas of the faces of the polyhedron

lateral area of a polyhedron

the sum of the areas of the lateral faces of a polyhedron.

net

a two-dimensional pattern that you can fold to form a three-dimensional figure

cylinder

a solid bounded by a cylindrical surface and two parallel planes (the bases)

right cylinder

A cylinder with the axis perpendicular to both bases.

lateral area of a cylinder

la=2πrh

surface area of a cylinder

SA=2πr²+2πrh

pyramid

a polyhedron having a polygonal base and triangular sides with a common vertex

regular pyramid

a pyramid whose base is a regular polygon and whose lateral faces are congruent isosceles triangles

circular cone

base is a circle & it has 1 vertex.

lateral surface of a cone

LSA = ½PL

(P is the perimeter/circumference of the base, L is the slant height)

(P is the perimeter/circumference of the base, L is the slant height)

right cone

A cone in which a perpendicular line drawn from the base to the tip (vertex) passes through the center of the base

volume of a solid

V=lwh

sphere

a three-dimensional closed surface such that every point on the surface is equidistant from the center

center of a sphere

The point inside a sphere that is the same distance from every point on the sphere.

radius of a sphere

a segment that has one endpoint at the center and the other endpoint on the sphere

chord of a sphere

a segment whose endpoints are on the sphere

diameter of a sphere

a segment passing through the center, with endpoints on the sphere

great circle

a circular line on the surface of a sphere formed by intersecting it with a plane passing through the center

hemisphere

half of a sphere

similar solids

solids with the same shape and all their corresponding dimensions are proportional