2007-09-13 15:46:56 · 18 answers · asked by Shaddy 1 in Science & Mathematics ➔ Mathematics
In Euclidean geometry, a circle is the set of all points in a plane at a fixed distance, called the radius, from a given point, the centre.
A circle is a special ellipse in which the two foci coincide (i.e., are the same point). Circles are conic sections attained when a right circular cone is intersected with a plane perpendicular to the axis of the cone.
The circle is the shape with the highest area for a given length of perimeter.
The circle is a highly symmetric shape, every line through the centre forms a line of reflection symmetry and it has rotational symmetry around the centre for every angle. Its symmetry group is the orthogonal group O(2,R). The group of rotations alone is the circle group T.
All circles are similar.
A circle's circumference and radius are proportional,
The area enclosed and the square of its radius are proportional.
The constants of proportionality are 2π and π, respectively.
The circle centred at the origin with radius 1 is called the unit circle.
2007-09-14 03:06:29 · answer #1 · answered by Rod Mac 5 · 0⤊ 0⤋
The locus of all the points equidistant from a fixed point. The fixed point is the center of the circle and fixed distance is the radius
2007-09-13 22:54:51 · answer #2 · answered by mohanrao d 7 · 0⤊ 0⤋
A circle is a series of connected points equally distant from a center point.
2007-09-13 22:51:02 · answer #3 · answered by Anonymous · 0⤊ 0⤋
It is the locus of an infinite number of points, all of which are equidistant from a common point (called the 'center' of the circle).
Doug
2007-09-13 22:54:12 · answer #4 · answered by doug_donaghue 7 · 0⤊ 0⤋
It's a round square. Two semi - circles. A circumference. Anything you want it to be really.
2007-09-13 22:59:17 · answer #5 · answered by tterb 1 · 0⤊ 0⤋
a circle is a line consisting of infinite number of points having the same locus (all equidistance to a point).
this locus is what is referred to as the centre.
2007-09-14 07:23:53 · answer #6 · answered by firebird 1 · 0⤊ 0⤋
It is the set of all points that is equidistant from another, fixed, point. When defined in a 2d Euclidean (say, standard x,y) space it looks like an "O"
2007-09-13 22:50:26 · answer #7 · answered by Anonymous · 0⤊ 0⤋
Geometrically speaking,
it's the set of all points (on a plane) at a fixed distance from a given point.
2007-09-13 22:51:08 · answer #8 · answered by Regina 1 · 0⤊ 0⤋
That curve for a fixed perimeter, which encloses the maximum area.
Wonder what is the maximum volume which can be enclosed by a given area?
2007-09-13 23:11:18 · answer #9 · answered by alienfiend1 3 · 0⤊ 0⤋
It's a thing with two wheels, a saddle, handlebars and a chain that your trouser bottoms keep getting caught up in . . . .
2007-09-13 23:17:28 · answer #10 · answered by Anonymous · 0⤊ 0⤋