The Side of an decagon is 18
Calculate perimeter, area
P = 10 x side
P = 10 x 18
P = 180
A = 5/2s2√5 + 2√5
A = 2.5(18)2(3.0776835371753)
A = 2.5(324)(3.0776835371753)
A = 2492.923665112
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