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March 26

Fundamental geometrics

Hello, sadly, I didn't learn much math in my past. Please help me.

It may be grasped as ridiculous but would it be correct to define the diameter of a circle as a chord going from the main point to one of the points of the circle's perimeter/circumference (a "Dimaterical chord")?

Thanks, 2001:44C8:455D:856A:5C60:9753:E93A:E68 (talk) 08:18, 26 March 2023 (UTC)[reply]

Circle $C$ with
  centre $O$
  radius $R$
  diameter $D$

I assume that by "the main point" of a circle you mean its centre. In geometry, a circle is a curve. If you want to include the interior, it is called a disk. The circle is merely the perimeter of the disk.

A line segment from any point of a circle to its centre is called a radius of that circle. All radii have the same length, which is called "the" radius of the circle.

A chord of a circle is any line segment connecting two points of the circle.

Any chord that passes through the centre is called a diameter of the circle; it connects two points of the circle that are diametrically opposed. All diameters have the same length, which is called "the" diameter of the circle and is equal to twice its radius. --Lambiam 11:23, 26 March 2023 (UTC)[reply]