Answer

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A = 3
P = 6.2442264170951
Sides (Edges) = 10
Faces = 1
Vertices = 10

↓Steps Explained:↓

The Area of an decagon is 3

Calculate side, perimeter

Calculate side:

A = 5/2s²√5 + 2√5

A = 2.5s²(3.0776835371753)

s² =	2 x A
	5 x 3.0776835371753

s² =	2 x 3
	5 x 3.0776835371753

s² =	6
	15.388417685876

s² = 0.38990363547949

s = √0.38990363547949

s = 0.62442264170951

Calculate Perimeter:

P = 10 x side

P = 10 x 0.62442264170951

P = 6.2442264170951

Calculate Sum of the Interior Angles:

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

Interior Angle Sum = (10 - 2) x 180°

Interior Angle Sum = 8 x 180°

Interior Angle sum = 1440°

Calculate decagon diagonals

Diagonals =	n(n - 3)
	2

Diagonals =	10(10 - 3)
	2

Diagonals =	10(7)
	2

Diagonals =	70
	2

Diagonals = 35

Calculate diagonals from 1 vertex:

1 vertex Diagonals = n - 3

1 vertex Diagonals = 10 - 3

1 vertex Diagonals = 7

Calculate number of Δ from 1 vertex:

Triangles = N - 2

Triangles = 10 - 2

Triangles = 8

Other Properties:

Sides (Edges) = 10

Faces = 1

Vertices = 10