How is a 2-Sphere 2D, yet a Cube is 3D?

Question

A 2-Sphere is 2D because any point on the surface of the sphere can be determinted with just two numbers.

How its a Cube 3D? Can't any point on the surface also be determined also be determinted with two numbers?

Answer 1

The sphere is not 2D, it is 3D.

The surface of a sphere can be treated as 2D (and can be mapped in various ways to a 2D plane).

The surface of a cube is 2D (and can be mapped to a plane).

Answer 2

Your'e right, the surface of a cube is 2D. If you include the volume inside the cube, then it is 3D.

Answer 3

You need x,y and z coordinates for a point on the surface of a sphere therefore it is 3D

You need x, y and z coordinates for a point on a cube too

A sphere cannot be ACCURATELY mapped in 2D,

A cube can, only for area but the Z point of reference is lost

Answer 4

For 3-D objects, you write 3 numbers not 2. Also, a cube has 6 sides. Remember to include the depth (volume). A sphere has depth, but it can't be measured. It would depend on where you measured. So imagine as a map.