Introduction to Area
Area is a property of all two-dimensional figures. It measures the combined length and width of a
region. In the following lessons we'll explore the area of regions in a plane, although area is also a
property of two-dimensional surfa
Circles and Polygons
Inscription and Circumscription
Certain geometric figures are created by combining circles with other geometric figures, such as
polygons. There are two simple ways to unite a circle with a polygon. One is inscription, and the
other i
Introduction to Circles
A circle is the set of all points equidistant from a given point. The point from which all the points on a
circle are equidistant is called the center of the circle, and the distance from that point to the circle is
called the radi
Circumference
The perimeter of a circle is called a special name other than perimeter: circumference. The
circumference of a circle is the length of the curve that encloses that circle. A circle is defined by only
two things: its center and its radius. Tw
Prisms and Cylinders
Prisms
A prism is a polyhedron whose faces consist of two congruent polygons lying in parallel planes and a
number of parallelograms. The sides of the parallelograms are the segments that join the
corresponding vertices of the two con
Characteristics of Circles
Special names are given to geometric figures that lie on or inside circles. Among these geometric
figures are arcs, chords, sectors, and segments.
Arc
The arc of a circle consists of two points on the circle and all of the point
Tangent Lines and Secant Lines
Tangent Lines
A tangent line is a line that intersects a circle at one point. Such a line is said to be tangent to that
circle. The point at which the circle and the line intersect is the point of tangency.
Figure %: A tange
Three Dimensions
Surfaces
Just like a curve is the basic building block for figures in a plane, a surface is the basic building block
for figures in space. A surface is essentially a curve with depth. Curves and surfaces are analogous
in many ways. If you
Regular Polyhedra and Spheres
Regular Polyhedra
Some of the most specialized geometric surfaces are the regular polyhedra. In the special cases
we've studied so far, the base or bases of a geometric surface is a special shape. In a regular
polyhedron, all
Perimeter
The perimeter of any region in a plane is the length of the curve or curves that bound the region. For
regions that aren't bound by line segments, the perimeter often requires calculus to calculate. For
polygons, the name regions that are bound
Pyramids and Cones
Pyramids
Another interesting kind of polyhedron is a pyramid. A pyramid is the union of a polygon with all of
the segments that have one endpoint on the polygon and the other endpoint at a specified point in
space that is not in the sam