What is a Polygon?

In this animated video I would like to talk about Polygons

Polygons are 2-dimensional closed shapes.

A closed shape does not have any openings, and all of the lines connect.

You can’t leave the inside of a closed shape without crossing a line.

Polygons have straight lines and do not have curves

A polygon has three parts.

Straight Lines

Vertices which are the point at which the lines intercept

Angles are formed by intercepting lines



There are several types of polygons

A regular polygon has equal lines and angles

An irregular does not have equals lines and angles



A concave polygon has one angle greater than 180 degrees

A convex polygon does not have any internal angles greater than 180 degrees



A simple polygon does not have any lines that cross over.

A complex polygon has at least one line that crosses over itself



Polygon names

Named after the number of sides and angles

Triangle 3 sides

Quadrilateral

Pentagon 5

Hexagon 6

Heptagon 7

Octagon 8

Nonagon 9

Decagon 10

Hendecagon 11

Dodecagon 12

After 12 sides it is acceptable to give the number of sides and then gon

For example 14 gon has 14 sides



You may also enjoy...

Polygon Song

https://www.youtube.com/watch?v=69lfT...



What is a polygon, and different shapes.

https://www.youtube.com/watch?v=dRtbC...

Leave a Comment geometry, moomoomath, octagon, polygon, shapes, triangle

Volume of a Pyramid

In this video you will learn how to find the volume of a pyramid

The formula you use to find the volume of a pyramid equals 1/3 base area times the pyramid height
The base area formula depends on the shape of the pyramid base.
For example, the base can be square,rectangular, or even triangular.
Here is a list of the formulas for calculating the base area of different types of pyramids.

Base area formulas

The reason why you multiply the base area and height by 1/3 is because you can fit three pyramids in an equal size prism.

The video works two examples of finding the volume of a pyramid.

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The 5 Postulates (Axioms) of Euclidean Geometry

What is Euclidean Geometry?
The word Geometry is derived from,
Geo which means Earth, and Metron  which means to measure.

Geometry is a branch of mathematics concerned with questions of shape, size, relative position of figures, and shapes. Euclidean Geometry is the study of geometry based on definitions, terms and the assumptions of the mathematician Euclid (330 B.C.)
It is the Geometry of flat surfaces
Euclid's wrote 13 books called the Elements and was the first comprehensive discussion of geometry, and is credited with developing the first comprehensive deductive system of geometry.

Euclidean Geometry can also be called plane Geometry which is the study of lines and shapes on a flat surface.

Euclidean Geometry can be illustrated on flat paper or a chalkboard.

On a flat surface all of the following will be true.

• The shortest distance between two points is a straight line.
• The angles in any triangle add to 180 degrees.
• A perpendicular line intersects another line at 90 degree angles.

Euclidean Geometry cannot describe all physical space such as curved space.
Non-Euclidean Geometry describes curved space.

Euclid’s 5 Postulates (Axioms)

• It is possible to draw a straight line from any point to any point
• If you have a straight line it is possible to extend in any direction to infinity
• It is possible to draw a circle given any center and a radius 
• All right angles are equal (congruent)
• If you have two straight lines, and a third line crossing them, and the sum of the interior angle measure of the two lines is less than two 90 degrees, then if you extend the lines, they will eventually cross on that side.

These 5 postulates are the foundation of Euclidean Geometry and they are all about points, lines, and planes.

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Leave a Comment 13 elements, 5 postulates, axioms, basic, euclid, euclidean geometry, flat geometry, geometry, plane geometry, postulates, shapes

What is a trapezoid?

A trapezoid has two parallel sides and two non-parallel sides. and four straight lines.

In this video you will learn the properties of a trapezoid including the,

• number of sides
• area formula
• how many sides are congruent
• how many sides of a trapezoid are parallel

Leave a Comment geometry, math, moomoomath, polygon, shapes, trapezoid