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Number of Sides |
Name |
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3 |
Triangle |
|
4 |
Quadrilateral |
|
5 |
Pentagon |
|
6 |
Hexagon |
|
7 |
Heptagon |
|
And so on… |
A polygon is a closed figure composed of three or more line segments that intersect at their endpoints. Each line segment is called the side. The intersection at the endpoints is called the vertex. Keep in mind that the number of sides and number of interior angles of a polygon are the same. Polygons are named according to the number of sides. A general way to name a polygon with n sides is to call it a n-gon (e.g., A 7-gon is a polygon with 7 sides).
2.1.2 Triangles
When lines meet each other they create shapes. A shape made by three lines is called a triangle. Tri means three; therefore triangle means that there are three angles. Triangles always have three interior angles. Triangles have different characteristics by which we can identify them. Angles of a triangle always add up to 180.
The following three types of triangles are categorized by their angles:
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An acute triangle is a triangle that has three acute angles: |
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An obtuse triangle is a triangle that has one obtuse angle: |
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A right triangle is a triangle that has a right angle |
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The hypotenuse is the side opposite the right angle and the legs are the sides that meet at the right angle. The following three types of triangles are categorized by their sides:
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An isosceles triangle is a triangle that has two equal sides: |
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An equilateral triangle is one that has three equal sides: |
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A scalene triangle is a triangle where no two sides are equal in length: |
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