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Polygons
An Introduction to Polygons

Shape

Classification

Triangle
3 sides
Tri means three

*
There are some special triangles that are important to know:
Equilateral: All three sides are the same length and all three angles are equal.
Isoceles: Two sides have the same length, the angles opposite the equal sides are equal.
Scalene: NO two sides have the same length and no two angles are equal.
Acute: All three angles are less than a right angle.
Obtuse: One angle is greater than a right angle.
Right: One angle is 90 degrees - a right angle.
Quadrilateral
4 sides
Quad means four
* There are some special quadrilaterals that are important to know:
Parallelogram: the opposite sides are parallel. The angles are also equal.
Rectangle: all the angles are right angles.
Square: all four sides are equal.

Rhombus: all four sides are equal, it looks like a square on a slant.
Trapezoid: two sides are parallel and two sides are not parallel.
Pentagon
5 sides
Pent means five
Hexagon
6 sides
Hex means 6
Octagon
8 sides
Oct means 8
Decagon
10 sides
Dec means 10

These shapes are only examples, there are several different shapes that can apply to these polygons.
Related Links
:
Measuring area and perimeter of shapes.
Geometry Tutorials

 

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