1Triangle
2Pentagon
3Hexagon
5Heptagon
6Octagon
7Dodecagon
The formula for the number of diagonals of an n-gon is n(n-1)/2 - n. So plug in n = 3,5,6,7,8,12 and get your answers.
1) 0
2) 5
3) 9
5) 14
6) 20
Diagonals of Polygons::
File Format: Microsoft Word - View as HTMLLook for a pattern in the number of diagonals and use this to predict how many diagonals in a 7 (heptagon) and 8 (octagon) sided polygon.
http://aecarlisle.com/homework/maths/Diagonals of Polygons.docHOME |
7) 54
ENJOY! :D
A polygonal diagonal passes from one vertex to another through the center of the polygon.
Only regular polygons with an even number of vertices have diagonals, and they have half as many diagonals as vertices. So...
Triangle 0
Pentagon 0
Hexagon 3
Heptagon 0
Octagon 4
Dodecagon 6
1. 0
2. 2
3. 3
5. 4
6. 5
7. 9
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What is the number of diagonals of these following polygons?