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The Side of an decagon is 20
Calculate perimeter, area
P = 10 x side
P = 10 x 20
P = 200
A = 5/2s2√5 + 2√5
A = 2.5(20)2(3.0776835371753)
A = 2.5(400)(3.0776835371753)
A = 3077.6835371753
Interior Angle Sum = (sides - 2) x 180°
Interior Angle Sum = (10 - 2) x 180°
Interior Angle Sum = 8 x 180°
Interior Angle sum = 1440°
Diagonals = | n(n - 3) |
2 |
Diagonals = | 10(10 - 3) |
2 |
Diagonals = | 10(7) |
2 |
Diagonals = | 70 |
2 |
Diagonals = 35
1 vertex Diagonals = n - 3
1 vertex Diagonals = 10 - 3
1 vertex Diagonals = 7
Triangles = N - 2
Triangles = 10 - 2
Triangles = 8
Sides (Edges) = 10
Faces = 1
Vertices = 10
s = 20