Question

can you match the teachers comments to the definitions?
definition of a circle
rubys definition: a 3 - dimensional shape whose boundary consists of all points equidistant from a fixed point (the center).
shriyas definition: the set of all points in a 2d plane such that for every point in the set there is exactly one other point in the set that is d (call it diameter) units away.
abhisheks definition: the set of all points in a plane that are the same distance (radius) away from some given point (center).
teachers comments
you are correct. nicely done!
this is incorrect. for example, your definition also allows for the following shape, which is just part of a circle: ⌒
are you thinking of a sphere?

Explanation:

Ruby's definition is for a sphere (3 - dimensional), not a circle. Shriya's definition is incorrect as it does not accurately define a circle. Abhishek's definition correctly defines a circle as the set of all points in a plane at a fixed distance (radius) from a given point (center).

Answer:

Ruby's definition - Are you thinking of a sphere?
Shriya's definition - This is incorrect. For example, your definition also allows for the following shape, which is just part of a circle: ⌒
Abhishek's definition - You are correct. Nicely done!