- In the homework reading, the following surfaces were not in R
^{3}:- Models of hyperbolic geometry
- Stereographic projection of the sphere
- Flat torus
- all of the above
- none of the above

upper half-plane model conformal, circles and angles

- Gauss curvature K is
- intrinsic
- extrinsic
- a vector
- both a and c
- both b and c