What's the difference between a circle and an ellipse?

Answer 1

A circle is the set of points equidistant from a single center.

An ellipse is the set of points where the sum of the distances from each point to 2 particular points (the foci) is the same. So, a circle is actually an ellipse where the two foci are a single point.

So, if you are a runner and every day want to run 6 miles, starting and ending at your home, all the locations you can run to would be a circle 3 miles in radius. If instead your run starts at home and ends at your school, 1 mile away, then the set of locations would be an ellipse.

One property of the ellipse is that if you put a light bulb at one focus of a mirrored ellipse, each light ray will reflect off the mirror and pass through the other focus. (this is why they are called "focus")

And, the earth is *not* closer to the sun in wintertime, since winter in the northern hemisphere is summer in the southern, and vice-versa. The seasons are caused by the slant of the earth's axis with respect to the plane of rotation. Geez.

Answer 2

A circle has one center and all the points are equidistant from that point.
An ellipse has two centers and the sum of the distances from those two is the same for all points on the ellipse. As the centers get closer together, the ellipse approaches a circle.
One way to draw an ellipse is to make a loop of string and run it around two tacks or nails at the centers then around the point of a pen or pencil. Moving the marker so the string says tight, the sum of distances stays the same (the length of the string minus the part between the two points) and the marker is forced to draw a circle.
Planets and other space bodies move in ellipses with the central body at one of the focuses.

Answer 3

The quick answer is : an ellipse is a squashed circle. It is not egg shaped (eggs have large bottoms and small tops) None of the answers given so far hit the nail on the head. a circle is a set of points that are exactly the same distance from a centre point, or focus (plural: foci). an ellipse is a set of points whose distances from two foci sum to the same constant. in other words, any line drawn from one focus, to the edge of the ellipse, and then to the other focus, should have the same length. By the way a circle is a special case of an ellipse, and a formal mathematical definition for an ellipse is given by "the intersection of a plane and a cone"

Answer 4

It's sort of like how a square is a form of a rectangle. A square is a rectangle but a rectangle is not necessarily a square.
It's the same with circle and ellipse. A circle is a form of an ellipse. An ellipse is anything that is round, it could be a circle or an oval. A circle has to have an equal radius all around but an ellipse does not.

Answer 5

the circle is just a special type of ellipse.

the difference is that an ellipse will have more than one focii while the cirlce only have one - the centre. all the points on the circle will be equidistant to the centre whereas in an ellipse, some points are further away than others.

in mathmatical terms that is:

the circle is teh locus of p(x,y) such that it is always equidistant from a fixed point (centre)

Answer 6

A circle is a set of points all of which are equidistant from a center point. The points on the edge of an ellipse are different distances from the center.

Answer 7

Ellipse is an oval shape like a flattened circle.

Circle is a shape consisting of a curved line completely surrounding an erea. Every part of the line is the same distance from the centre of the area.

Answer 8

an ellipse is like an oval. The planets travel in a ellipse. We are actually closer to the sun in the winter.

Answer 9

A circle is a special case of an ellipse.
A circle has an eccentricity of zero.

Answer 10

Circles are round. Ellipeses are round-ish.