Circles are defined as a shape with a continuous and even curvature, so they are generally considered to be perfectly round. However, in reality, there may be slight variations in the roundness of a circle due to imperfections in its construction or measurement.
No, a circle cannot have a radius of zero. A radius is defined as the distance from the center of a circle to its edge, so if the radius were zero, the circle would essentially be a single point.
Yes, by definition, all points on the circumference of a circle are equidistant from the center. This is what makes a circle a unique and distinct shape.
No, circles do not have sides. Unlike polygons, which have a finite number of sides, a circle is a continuous curve with no distinct edges or sides.
No, a circle cannot have a negative radius. A radius is a measure of distance and therefore cannot be negative. However, a circle can have a negative curvature, which would result in an inverted or "inside-out" circle.