Exploring Geometry

Errata (Blue Cover Draft)

This web page lists errors that have been discovered in the draft version (blue cover) of the text Exploring Geometry, by Mike Hvidsten.  Please note that any changes involving mathematical notation are expressed in TeX form.
If you discover errors other than those listed, please email them to hvidsten(at)gustavus.edu


Page(s)
 Line(s)
 Description
 Date
 Discoverer
17
 18
 Replace "B, and G" by "B, and J"       
 8-23-2003
 M Hvidsten
17
 20
 Replace "AG" by "AJ"         
 8-23-2003
 M Hvidsten
17
 22
 Replace "EF" by "GH"      
 8-23-2003
 M Hvidsten
17
 23
 Replace "AGFC" by "AJHC"         
 8-23-2003
 M Hvidsten
20
 5
 Delete "em"   
 8-26-2003
 M Wiest's class
21
 16
 Replace Axiom A2 with  "For every pair of students there is exactly one class."
 8-26-2003
 M Wiest's class
22
 3
 Capitalize "axiom"
 8-28-2003
 M Wiest's class
22
 29
 Replace Axiom A2 with  "For every pair of snarks there is exactly one bittle."
 9-01-2003
 M Hvidsten
22
 31
 Switch the words "snarks" and "bittles".
 8-28-2003
 M Wiest's class
24
 33 (Ex 1.4.3)
 Replace "Give" with "Given"
 8-28-2003
 M Wiest's class
24
 34
 Insert "different" between "two" and "flavors"
 9-01-2003
 M Hvidsten
26
 2
 Replace "x in in" with "x is in"
 9-16-2003
 R Batalden
34
 8
 Replace "A3" with "A2"
 9-01-2003
 M Hvidsten
62
 2
 Insert ",but is not coincident with," after "intersects".
 9-05-2003
 M Hvidsten
65
 20(Ex 2.2.2
 Insert ",but not one of the vertices," after "a rectangle".
9-05-2003
 M Hvidsten
75
 32(Ex 2.4.5)
 Replace "Covince" with "Convince"
 9-08-2003
 M Hvidsten
79
 18 (Ex 2.4.9)
  Replace "Show that the medians" with "The medians"
 9-08-2003
 M Hvidsten
85
 4
 Replace "to A, and right" with "to the angle at A, and a right"
9-10-2003
 M Hvidsten
85
 16
 Replace " if b and b" with "if a and b"
 9-10-2003
 M Hvidsten
85
 18
 Insert "sin" on the top and bottom of the fraction on the right side of the equal sign.
 9-10-2003
 M Hvidsten
85
 24 (Ex 2.5.7)
 Replace "B,C" with "A,B".
 9-10-2003
 M Hvidsten
85
 28
 Replace the second denominator term "AB" with "RB".
 9-10-2003
 M Hvidsten
91
 10
 Insert "convex" before "quadrilateral.
 9-13-2003
 M Hvidsten
95
 13(Ex 2.6.4)
 Replace the hint with "Assume that T is not on the line through the centers. Consider the perpendicular l from T to this line. Use a triangle argument to show a second intersection exists."
9-13-2003
 M Hvidsten
95
 17 (Ex 2.6.5)
  Add the following: "[Hint: Let $m$ be the line through the centers. Consider the two radii that are perpendicular to the line through the centers.  Let $l$ be the line through the endpoints of these radii on their respective circles.  If $l$ and $m$ are parallel, show that $l$ is a common line of tangency for both circles. If $l$ and $m$ intersect at $P$, let $n$ be a tangent from $P$ to one of the circles. Use similar triangles to show $n$ is tangent to the other circle.
9-13-2003
 M Hvidsten
107
 14
 Replace "the y-axis from O" with "the x-axis"
 10-8-2003
 M Hvidsten
107
 21
 Add ", with A \ne (0,0)" after "origin"
10-8-2003 M Hvidsten
119
 Figure for Ex 3.3.1
  The angle labeled "b" should be "\beta"
 10-8-2003 M Hvidsten
119
 11 (Ex 3.3.2)
 Replace "90" with "\frac{\pi}{2}"
 10-8-2003 M Hvidsten
129
 6 (Ex 3.4.6)
 There should be parentheses around the term "P'-N"
 10-8-2003 M Hvidsten
132
 5
 Replace "simple" with "simply"
 10-12-2003 M Hvidsten
132
 6
 Replace "parameter t as described." with
"parameter t \sqrt{dx^2 + dy^2}."		 10-12-2003 M Hvidsten
133
 33 (Ex 3.5.2)
 Delete "be"
10-12-2003 M Hvidsten
140
 19(Ex 4.1.2)
 Replace "that" with "the"
 10-12-2003 M Hvidsten
147
 Theorem 4.9
 Second sentence in theorem should read "Then, for all points A \ne B, if A, B, T(A), T(B) form a quadrilateral, then that quadrilateral is a parallelogram."
10-12-2003 M Hvidsten
148
10
 Replace "By theorem 2.4.1" with "By constructing the diagonal of the quad, and using a triangle congruence argument, we see that "
 10-12-2003 M Hvidsten
155
 7
 Add "or the identity," after "cannot be a rotation".
 10-20-2003 M Hvidsten
155
 20
 Replace "B \ne A" with "B \ne O"
 10-20-2003 M Hvidsten
159
 1 (Ex 4.4.4)
 Add " \ne 0" after "is a rotation of \theta"
 10-20-2003 M Hvidsten
159
 6 (Ex 4.4.5)
 Add "\ne id" after "if a rotation R_O"
10-20-2003 M Hvidsten
155
 23
 Replace "previous theorem" with "proof of Theorem 4.13"
 10-20-2003 M Hvidsten
166
 3
 Delete "(non-identity)"
 10-20-2003 M Hvidsten
168 Theorem 4.19
 Delete "(non-identity)" 10-20-2003 M Hvidsten
174
 13, 14
 Add "(mod 360)" after "0" in both lines.
 10-30-2003
 M Hvidsten
179
 Table 4.1
 In the second entry of the last row, replace both occurrences of "l" to "m".
11-5-2003
 M Hvidsten
179
 18 (Ex 4.7.3)
 Replace "an isometry f" with "a direct isometry f"
 10-20-2003 M Hvidsten
180
 2
 Replace "be" with "by".
 11-5-2003
 M Hvidsten
182
 19
 Replace "R_{A,\angle{EAB} and R_{B,\angle{ABE}" with "R_{B,\angle{ABE} \circ R_{A,\angle{EAB}". 11-5-2003
 M Hvidsten
190
 13
 Replace "r_l \circ R_{a,\alpha}" with
"r_l \circ R_{a,i \alpha}"		 11-5-2003
 M Hvidsten
195
 3
 Replace "H_A \circ H_B" with "H_B \circ H_A".
 11-5-2003
 M Hvidsten
196
 25-31
 Replace all occurences of "\epsilon" with "\delta".
 11-5-2003
 M Hvidsten
197
 1,2
 Replace "\epsilon" with "\delta". 11-5-2003 M Hvidsten
202
 36
 Replace "or q" with "or c".
 11-5-2003 M Hvidsten
204
 Ex 5.2.4
 Replace the first sentence with "Let G be a wallpaper group, and let H be the subset of all
symmmetries fixing a point of the lattice for G."

Also, in the second sentence replace "show G must be the group ..." with "show H must be the group ..."
 11-8-2003
 M Hvidsten
204
 Ex 5.2.5
 Replace "show that the lattice for G must be rectangular." with "show that the lattice for $G$ must be rectangular, square, or centered rectangular. " 11-8-2003
 M Hvidsten
222
 3
 Replace "M\"oebius" with "M\"obius".  This is a global error throughout the text.  10-23-2003 G Francis
225
 Ex 6.2.5
 Replace "Show that the composition t \circ S" with "Show that the composition T \circ S"
 11-8-2003
 M Hvidsten
231
 -2 (from bottom)
 There is a missing right parentheses.
 10-23-2003 G Francis
232
 3
 Accent on "Poincar\`e" is wrong. It should be "Poincar\'e".
This is a global error throughout the text.
10-23-2003
 G Francis
236
 Ex 6.3.10
 Replace  "Prove (i), (ii) ..." with  "For the function d_H prove (i), (ii) ..."
 11-8-2003
 M Hvidsten
241
 11
 The terms "PF" and "PQ" should be overlined.
 11-8-2003 M Hvidsten
241
 12
 Insert ",PD," after "rotate PF".
 11-8-2003 M Hvidsten
241
 13
 Replace "\angle{QPF}" with "\angle{FPQ}".
11-8-2003 M Hvidsten
242
 4
 Delete "is".
 11-8-2003 M Hvidsten
247
 20 (Ex 6.4.8)
 The term "PR" should have a double arrow above.
11-8-2003 M Hvidsten
247
 24
 "Theorem" should not be capitalized.
 11-8-2003 M Hvidsten
247
 25
 Delete "is".
 11-8-2003 M Hvidsten
255
 1
 The term "CD" should have a double arrow above. 11-18-2003
 M Hvidsten
258
 9
Replace "larger that" with "larger than".
 11-18-2003
 M Hvidsten
258
 Ex 6.6.2
 Switch the words "summit" and "base".
 11-18-2003 M Hvidsten
264
 6
 The term "EF" should have a double arrow above.