a straight line passing from side to side through the center
u define a circle by asking www.dictionary.reference.com
Yes. The center is the mid-point of the segment, and that's all you need to uniquely define a circle.
No. Every circle on the sphere whose center is also the center of the sphere is a great circle. If the circle's center is not also the center of the sphere, then the circle is a small circle.
No it's made by the circle that how they get the circle not the center.
A RADIUS connects the center of a circle to any point on the circle.
This circle is called the center circle.
The cord of a circle that contains the center of that circle is a diameter of that circle.
The circumference of a circle is the distance around it.
Knowing two points on a circle does not define a unique circle, so it is impossible to find the centre of the circle as there are infinitely many centres possible.
A chord of a circle that contains the center of the circle is called the diameter.