If you mean the area of a regular octagon with 8 equal sides of 3 cm then by using trigonometry its area works out as 43.36 square cm rounded to two decimal places.
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The flat shape (2-D) is an octagon. An eight-sided solid is an octahedron.
Formula for number of diagonals in an n-sided polygon is: number_of_diagonals = n x (n - 3) / 2 For an octagon, put n=8 in the above to get: number_of_diagonals_in_an_octagon = 8 x (8 - 3) / 2
9 square centimetres.
There are 20 diagonals in an 8 sided octagon
In geometry a 29 sided shape is referred to as an icosikaidigon. The shape closely resembles an 3 dimensional octagon.
An octagon is an 8 sided 2 dimensional shape. A cylinder with the base of a hexagon (6 sided shape) would be an 8 sided 3 dimensional shape.
An octagon is an eight-sided figure. If a regular octagon has a perimeter of 24 inches, then each side will be 24 / 8 = 3 inches.
We have the triangle (3-sided), square (or quadrilateral, 4-sided), pentagon (5-sided), hexagon (6-sided), heptagon (or septagon, 7-sided), octagon (8-sided), nonagon (9-sided) and decagon (10-sided) to get you started.
The area of a 3 cm circle is: 7.069 square cm
For a plain 2-dimensional figure it is an OCTAGON. For a 3-dimensional object it is an OCTAHEDRON.
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A circle with a radius of 3 cm has an area of 28.27 square cm.
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18 cm
The flat shape (2-D) is an octagon. An eight-sided solid is an octahedron.