Calculate Irregular Octagon

Calculator and formulas for the elongated octagon

Irregular Octagon Calculator

The irregular octagon

An irregular octagon is an elongated octagon with two different side lengths but equal interior angles of 135°.

Enter octagon parameters
6 sides with this length
2 sides with this length
Octagon structure

Special features: All interior angles = 135°, elongated form

6 × a sides 2 × b sides 8 × 135° angles
Octagon calculation results
Length l:
Height h:
Diagonal d:
Perimeter P:
Area A:

Octagon structure

The irregular octagon has two different side lengths.
All interior angles are uniformly 135°.

irregular octagon

The irregular elongated octagon

The irregular octagon is a special form of octagon with unique properties:

  • Eight sides: 6 sides of length a, 2 sides of length b
  • Equal angles: All interior angles are 135°
  • Elongated form: Rectangular middle part with beveled corners
  • Simple calculation: Only two parameters required
  • Practical form: Common in technical applications
  • √2 relationships: Mathematically elegant proportions

Angle properties

The angle structure of the irregular octagon is remarkably uniform:

Interior angles
  • All 8 interior angles = 135°
  • Sum: 8 × 135° = 1080°
  • Matches octagon formula: (8-2) × 180°
  • 45° more than right angle
Exterior angles
  • All 8 exterior angles = 45°
  • Sum: 8 × 45° = 360°
  • Matches general polygon rule
  • Half right angle per corner

Geometric structure analysis

The geometric structure of the elongated octagon:

Construction principle
  • Middle part: Rectangle of size (b-a) × h
  • Side parts: 2 squares of size a × a
  • Corners: 4 beveled 45° triangles
  • Symmetry: Horizontally and vertically symmetric
√2 mathematics
  • Height: h = a(1 + √2)
  • Length: l = a(1 + √2) + b - a
  • √2 ≈ 1.414: Fundamental for 45° geometry
  • Elegant formulas: Minimal complexity

Applications of the irregular octagon

The elongated octagon finds diverse practical applications:

Mechanical engineering & technology
  • Special tool profiles
  • Pipeline cross-sections
  • Gear and cam forms
  • Structural hollow profiles
Architecture & construction
  • Window and door openings
  • Column and pillar profiles
  • Decorative wall elements
  • Pavilion and gazebo floor plans
Design & art
  • Furniture design and tabletops
  • Logo design and symbols
  • Jewelry and decorative objects
  • Textile patterns and ornaments
Traffic & infrastructure
  • Road signs and traffic signs
  • Tunnel and bridge profiles
  • Parking lot and area markings
  • Guard rails and barriers

Formulas for the irregular octagon

Length l
\[l = a(1 + \sqrt{2}) + b - a\]

Total length of the elongated octagon

Height h
\[h = a(1 + \sqrt{2})\]

Height based only on short side a

Perimeter P
\[P = 6a + 2b\]

6 short sides plus 2 long sides

Diagonal d
\[d = \sqrt{l^2 + h^2}\]

Pythagorean theorem applied to length and height

Area A
\[A = 2a^2(1 + \sqrt{2}) + h(b - a)\]

Composed of squares, triangles and rectangle

√2 constant
\[\sqrt{2} \approx 1.4142\]

Fundamental for 45° angle geometry

Interior angles
\[8 \times 135° = 1080°\]

All interior angles are equal

Calculation example for an irregular octagon

Given
Short side a = 4 Long side b = 10

Find: All geometric properties of the elongated octagon

1. Calculate basic dimensions
\[h = 4 \times (1 + 1.414) = 9.66\] \[l = 9.66 + 10 - 4 = 15.66\]

Height and total length

2. Perimeter and diagonal
\[P = 6 \times 4 + 2 \times 10 = 44\] \[d = \sqrt{15.66^2 + 9.66^2} = 18.35\]

Total perimeter and main diagonal

3. Area calculation
Square portion: 2 × 16 × 2.414 = 77.25
Rectangle portion: 9.66 × 6 = 57.96
Total area A = 135.21

Composition from different geometric elements

4. Complete irregular octagon
Short side a = 4.00 Long side b = 10.00 Height h = 9.66 Length l = 15.66
Perimeter P = 44.00 Diagonal d = 18.35 Area A = 135.21 8 × 135° angles!

The complete elongated octagon - practical form with elegant mathematics

The irregular octagon: Practical geometry

The irregular elongated octagon is a fascinating example of how practical requirements can lead to elegant geometric solutions. As an octagon with two different side lengths but uniform interior angles, it combines the simplicity of regular forms with the flexibility of irregular constructions, finding broad application in technology and design.

Geometric elegance despite irregularity

The special feature of the elongated octagon lies in its structural clarity:

  • Uniform angles: All 8 interior angles are exactly 135°
  • Two side lengths: 6 short sides (a) and 2 long sides (b)
  • √2 mathematics: All relationships based on √2 ≈ 1.414
  • Modular construction: Rectangular middle part with beveled ends
  • Symmetric structure: Horizontally and vertically mirror-symmetric
  • Simple formulas: Despite irregularity, mathematically manageable

The 135° angle: Geometric perfection

The uniform interior angle of 135° makes this octagon special:

Mathematical significance

135° = 90° + 45°, the perfect combination of right angle and 45° bevel. This enables both orthogonal and diagonal construction elements.

Constructive advantages

The 135° angle allows clean transitions between horizontal/vertical and diagonal elements, ideal for manufacturing and assembly processes.

Aesthetic harmony

The 45° bevels (exterior angles) create visual dynamism while uniform angles provide calm and order.

Practical application

Standard tools and machines can easily execute 45° cuts, simplifying manufacturing and reducing costs.

Versatile practical applications

The elongated octagon finds application in many areas:

  • Mechanical engineering: Profiles for shafts, pipes and structural components
  • Architecture: Columns, pillars and decorative elements
  • Traffic engineering: Signs, markings and guardrail profiles
  • Furniture design: Tabletops, frames and functional elements
  • Electronics: Housing and heat sink profiles
  • Optics: Lens and prism forms for special applications

Mathematical considerations and optimization

The mathematical structure enables interesting optimization approaches:

Area optimization

For a given perimeter, the ratio a:b can be chosen so that the area is maximized or optimized for special requirements.

Material efficiency

The simple formulas allow precise material requirement calculation and waste optimization in industrial manufacturing.

Structural analysis

The uniform angles simplify stress analysis and enable precise predictions about load capacity and deformation.

Manufacturing aspects

Reduction to only two parameters (a and b) significantly simplifies design, manufacturing and quality control.

Summary

The irregular elongated octagon exemplifies how mathematical elegance and practical applicability can go hand in hand. Its apparent irregularity conceals a deep geometric order: The uniform 135° angles create structural clarity while the two different side lengths provide the necessary flexibility for diverse applications. From √2-based mathematics to industrial manufacturing, this form demonstrates that true geometric beauty does not lie in perfect regularity, but in the intelligent balance between order and adaptability. In a world that demands both efficiency and versatility, the elongated octagon offers an optimal solution - mathematically well-thought-out, technically feasible and aesthetically appealing.

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