Answer

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s = 5
P = 40
A = 120.71067811865
Interior Angle sum = 1080°
Diagonals = 20
1 vertex Diagonals = 5
Triangles = 6
Sides (Edges) = 8
Faces = 1
Vertices = 8

↓Steps Explained:↓

The Side of an octagon is 5

Calculate perimeter, area

Calculate Perimeter:

P = 8 x side

P = 8 x 5

P = 40

Calculate Area:

A = 2(1+√2)side²

A = 2(2.4142135623731)5²

A = 4.8284271247462(25)

A = 120.71067811865

Calculate Sum of the Interior Angles:

Interior Angle Sum = (sides - 2) x 180°

Interior Angle Sum = (8 - 2) x 180°

Interior Angle Sum = 6 x 180°

Interior Angle sum = 1080°

Calculate polygon diagonals

Diagonals =	n(n - 3)
	2

Diagonals =	8(8 - 3)
	2

Diagonals =	8(5)
	2

Diagonals =	40
	2

Diagonals = 20

Calculate 1 vertex diagonals:

1 vertex Diagonals = n - 3

1 vertex Diagonals = 8 - 3

1 vertex Diagonals = 5

Calculate triangles from one vertex:

Triangles = N - 2

Triangles = 8 - 2

Triangles = 6

Other Properties:

Sides (Edges) = 8

Faces = 1

Vertices = 8

Final Answers