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Q: How many diagonals in decagon?

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A tetra-decagon is a 14 sided polygon having 77 diagonals

35

A decagon has 35 diagonals. A Nonagon has 27 diagonals. An Octagon has 20 diagonals. A Heptagon has 14 diagonals. A Hexagon has 9 diagonals. A Pentagon has 5 Diagonals. A Square has 2 Diagonals. A triangle has 0 Diagonals.Do you get the point?0+2+3+4+7+8. Starting with the triangle.you don't need to start with the triangle because it is 0 diagonals and will not count when you add it up anyways. And don't call it a square, call it a quadrilateral.Shut up-------Imagine a hexagone-There are two vertices at the top which make a horizontal line- Opposite them there are 2 vertices on the bottom which we can draw straight lines totherefore-There would have been 6 connections per point, but we eliminated 3(n-3)---The connections occur for every vertex in the shapethereforen(n-3)--We don't want to draw the same connections twice once we get around to vertices on the opposite side of the shapethereforen/2(n-3)where n is the number of facesThis may be applied to many if not all polygons. A Decagon has 36 sides not 35...There are 35 diagonals in a 10 sided decagon

8

it depends on what you mean by a diagonal. If you take a diagonal to mean a line from one corner to the "opposite" corner, then a nonagon doesn't have any, and a decagon has five. The reason a nonagon doesn't have any, is that the corners aren't opposite each other.

Related questions

A tetra-decagon is a 14 sided polygon having 77 diagonals

35.

35

35

A decagon has 10 sides and 35 diagonals

35 diagonals

35 diagonals

54 Diagonals. * * * * * A polygon with n sides has 1/2*n*(n-3) diagonals. So a decagon would have 1/2*10*7 = 35 diagonals. How the Community answer got 54 is anybody's guess!

decagon

A decagon has 35 diagonals

There are 8

It is: 0.5*(10 squared - (3*10)) = 35 diagonals