Answer

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A = 15
s = 0.56735803656047
P = 4.5388642924837
Interior Angle sum = 1080°
Diagonals = 20
1 vertex Diagonals = 5
Triangles = 6
Sides (Edges) = 8
Faces = 1
Vertices = 8

↓Steps Explained:↓

The Area of an octagon is 15

Calculate side, perimeter

Calculate side:

s =	√2(1+√2)
	√A

s =	√2(2.4142135623731)
	√15

s =	√4.8284271247462
	√15

s =	2.1973682269356
	3.8729833462074

s = 0.56735803656047

Calculate Perimeter:

P = 8 x side

P = 8 x 0.56735803656047

P = 4.5388642924837

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