The circle (old high German: circil, of lat.: circulus: Circular path) is equipment used in even Euclidean geometry, which draws a circle around a given point.

In the antique one the circle beside the ruler was the only permitted aid to the construction of geometrical objects (see also classical problems of antique mathematics), since mental the Platonic ideals circle and straight line were the basis for them (see idea teachings).

A circle consists of two usually metallic staffs of equal length, that are articulated connected at an end in each case. One of the staffs has a point (needle) at its other end, which serves for the adjustment of the circle on the document. With fixing the Kreismittelpunkt is put firmly, with the distance of the second thigh to first the radius.

At the end of the second, mobile staff usually is a device, with which the circle or circle section on the document is drawn. For drawing dependent on the underground different devices are used. On paper a pencil mine becomes (at school) or a device for india ink (technical designs) on Pergament uses. For representations of circles on other materials, for example leather, is used chalk. On metallic surfaces a drawing pin is used.

Between both thighs a mechanism can be present for the determination of the distance. The simplest and most inaccurate realization is a threaded rod with a centrically existing knurled thumb screw. More exact circles contain at in-stung, firmly standing thigh a Millimeterteilung or a vernier. The exact distance between the thigh points is read off from the mobile thigh.

Today in the school teaching beside the circle and ruler also the geo triangle and dynamic geometry software are used.

A further variant of the circle, with which one does not draw, but only lengths to measure can, is the Stechzirkel. It is used for example in the navigation with navigation after maps.

A simple circle can be designed from a nail or needle for the establishment of the center, a thread or cord for the determination of the radius and a pin for drawing. The ends of the thread/the cord are wound around pin and nail, which must suitable radius by trying by means of rolling up are determined.

"… and if one does not have degree a circle, but although needs one, one uses the gardner construction.

Archai application for the construction of the even pentagon and from it derived the Pentagramms, see also: Pentagon

Articles in category "Circle"

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Related Websites

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