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 Home | Forms | Imprint & Privacy Geometric Calculators German: Geometrierechner

2D Regular Polygons:
Equilateral Triangle, Square, Pentagon, Hexagon, Heptagon, Octagon, Nonagon, Decagon, Hendecagon, Dodecagon, N-gon

Other Polygons:
Triangle, Right Triangle, Isosceles Triangle, IR Triangle, Rectangle, Rhombus, Parallelogram, Kite, Isosceles Trapezoid, Trapezoid, Cyclic Quadrilateral, Tangential Quadrilateral, Arrowhead, Concave Pentagon, Pentagram, Hexagram

Round Forms:
Circle, Semicircle, Circular Sector, Circular Segment, Round Corner, Annulus, Ellipse, Stadium, Digon, Spherical Triangle, Reuleaux Triangle, Astroid, Cardioid, Parabolic Segment, Arbelos, Lune
3D Platonic Solids:
Tetrahedron, Cube, Octahedron, Dodecahedron, Icosahedron

Archimedean Solids:
Truncated Tetrahedron, Cuboctahedron, Truncated Cube, Truncated Octahedron, Rhombicuboctahedron, Truncated Dodecahedron, Truncated Icosahedron

Other Polyhedrons:
Cuboid, Square Pyramid, Pyramid, Frustum, Bipyramid, Right Wedge, Wedge, Rhombohedron, Parallelepiped, Prism, Antiprism, Disphenoid, Truncated Rhombohedron, Stellated Octahedron, Small Stellated Dodecahedron

Round Forms:
Sphere, Hemisphere, Cylinder, Cut Cylinder, Oblique Cylinder, Cone, Truncated Cone, Ellipsoid, Spherical Sector, Spherical Cap, Spherical Segment, Spherical Wedge, Cylindrical Sector, Cylindrical Segment, Torus, Spherical Ring, Capsule, Lens, Paraboloid, Oloid

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# Octagon Calculator

Make calculations in a regular octagon (8 vertices). This form is familiar from being used as stop sign. Enter one value and choose the number of decimal places. Then click Calculate.

 Edge length (a): Long diagonal (d): Medium diagonal (e): Short diagonal (f): Perimeter (p): Area (A): Excircle radius (re): Incircle radius (ri): Round to   0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15   decimal places.

Formulas:
d = a * √ 4 + 2 * √2
e = a * ( 1 + √ 2 )
f = a * √ 2 + √2
Height = e = 2 * ri
p = 8 * a
A = 2 * a² * ( 1 + √2 )
re = a / 2 * √ 4 + 2 * √2
ri = a / 2 * ( 1 + √2 )
Angle: 135°
20 diagonals

Edge length, diagonal, height, perimeter and radius have the same unit (e.g. meter), the area has this unit squared (e.g. square meter).

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