The following are all the errata that I know of. The changes are indicated in red. If you see other errata please send me a message at dwh2@cornell.edu. I thank those (indicated below) who pointed out to me these errors.

**Corrected for 2nd printing:**

- page xvii, line 7- (Preface): "www.math.cornell/~dwh/books/eg00/supplements"
- Pointed out to me by Jeff Johannes, University of Nevada, Las Vegas.

page 47, lines 9- - 7- (A Short History of Hyperbolic Geometry): "In 1964, N. V. Efimov [**NE**: Efimov] extended Hilbert's result by proving that there is no isometric embedding defined by functions whose first and second derivatives are continuous."

- Pointed out to me by Konstantin Rybnikov, Cornell University.

page 59, line 1: Equation should be: " "

- Pointed out to me by Jeff Johannes, SUNY Geneseo.

- I found this mistake while teaching at the University of Latvia.

"

- I found this mistake while reading homeworks at the University of Latvia.

page 195, bottom, and 196, top: The three occurrences of the limit "*x*®0" should be "*t*®0".

- This was pointed out to me by Gian Mario Besana, Indiana University Northwest.

page 266, lines 7- - 6- (Problem 20.1): "*There's no way within *2*-space to move the mitten to fit the other hand *(without turning it inside out)*.*"

- Pointed out to me by Derek Rhodes.

- Pointed out to me by J. William Helbron, Upland, CA.

"N. V. Efimov, "Generation of singularities on surfaces of negative curvature [Russian]", Mat. Sb. (N.S.) 64 (106), pp. 286-320, 1964.

- Efimov proves that it is impossible to have a
*C*^{2}isometric embedding of the hyperbolic plane onto a closed subset of Euclidean 3-space. These results are clarified for English-reading audiences in [**NE:**Milnor]." - Pointed out to me by Konstantin Rybnikov, Cornell University.

"Milnor, Tilla, Efimov's theorem about complete immersed surfaces of negative curvature,

- Milnor clarifies for English readers the result in [NE: Efimov]."
- Pointed out to me by Konstantin Rybnikov, Cornell University.

"Hilbert, David, and S. Cohn-Vossen,

- They state "it is our purpose to give a presentation of geometry, as it stands today [1932], in its visual, intuitive aspects." It includes an introduction to differential geometry, symmetry, and patterns (they call it "crystallographic groups"), and the geometry of spheres and other surfaces. Hilbert is the most famous mathematician of the first part of the 20th century."

"trisection, 186"

**Corrected for 3nd printing:**

page 10, line 6-: "Problem **1****4****.3b**. See [**SE**: Hilbert, pp. 272-73] for another discussion of"

page 35, lines 14- & 10-: "Problem **1****7****.1**"

- Pointed out to me by Colm Mulcahy, Spelman College.

- Pointed out to me by Barbara Edwards, Oregon State University.

page 181, line 9: "site: **http://pi.math.cornell.edu/~dwh/books/eg****00/**."

- Pointed out to me by Eric Bray, Cornell student.

- The error was pointed out to me by Nir Yehoshua Etzion, Cornell student.

- Pointed out to me by Laura Ann Ruganis, Cornell student

- Pointed out to me by Laura Ann Ruganis, Cornell student

- Pointed out to me by Laura Ann Ruganis, Cornell student

- Pointed out to me by Douglas C. Mitarotonda, Cornell student.