| Preface |
|
xi | |
| Preliminaries |
|
xiii | |
| 0.1 The Structure of This Book |
|
xiii | |
| 0.2 Centers of a Triangle |
|
xiv | |
| 0.3 Other Notations and Conventions |
|
xv | |
|
|
|
1 | (72) |
|
|
|
3 | (20) |
|
1.1 Triangles and Circles |
|
|
3 | (3) |
|
1.2 Cyclic Quadrilaterals |
|
|
6 | (1) |
|
|
|
7 | (2) |
|
1.4 The Incenter/Excenter Lemma |
|
|
9 | (2) |
|
|
|
11 | (4) |
|
1.6 Tangents to Circles and Phantom Points |
|
|
15 | (1) |
|
1.7 Solving a Problem from the IMO Shortlist |
|
|
16 | (2) |
|
|
|
18 | (5) |
|
|
|
23 | (20) |
|
2.1 Orientations of Similar Triangles |
|
|
23 | (1) |
|
|
|
24 | (2) |
|
2.3 The Radical Axis and Radical Center |
|
|
26 | (4) |
|
|
|
30 | (1) |
|
2.5 Revisiting Tangents: The Incenter |
|
|
31 | (1) |
|
|
|
32 | (2) |
|
|
|
34 | (5) |
|
|
|
39 | (4) |
|
|
|
43 | (16) |
|
3.1 The Extended Law of Sines |
|
|
43 | (1) |
|
|
|
44 | (2) |
|
3.3 Directed Lengths and Menelaus's Theorem |
|
|
46 | (2) |
|
3.4 The Centroid and the Medial Triangle |
|
|
48 | (1) |
|
3.5 Homothety and the Nine-Point Circle |
|
|
49 | (2) |
|
|
|
51 | (5) |
|
|
|
56 | (3) |
|
4 Assorted Configurations |
|
|
59 | (14) |
|
4.1 Simson Lines Revisited |
|
|
59 | (1) |
|
4.2 Incircles and Excircles |
|
|
60 | (2) |
|
4.3 Midpoints of Altitudes |
|
|
62 | (1) |
|
4.4 Even More Incircle and Incenter Configurations |
|
|
63 | (1) |
|
4.5 Isogonal and Isotomic Conjugates |
|
|
63 | (1) |
|
|
|
64 | (2) |
|
4.7 Circles Inscribed in Segments |
|
|
66 | (2) |
|
4.8 Mixtilinear Incircles |
|
|
68 | (2) |
|
|
|
70 | (3) |
|
|
|
73 | (74) |
|
|
|
75 | (20) |
|
5.1 Cartesian Coordinates |
|
|
75 | (2) |
|
|
|
77 | (2) |
|
|
|
79 | (2) |
|
|
|
81 | (3) |
|
|
|
84 | (7) |
|
|
|
91 | (4) |
|
|
|
95 | (24) |
|
6.1 What is a Complex Number? |
|
|
95 | (1) |
|
6.2 Adding and Multiplying Complex Numbers |
|
|
96 | (3) |
|
6.3 Collinearity and Perpendicularity |
|
|
99 | (1) |
|
|
|
100 | (3) |
|
|
|
103 | (3) |
|
6.6 Complex Incenter and Circumcenter |
|
|
106 | (2) |
|
|
|
108 | (7) |
|
6.8 When (Not) to use Complex Numbers |
|
|
115 | (1) |
|
|
|
115 | (4) |
|
7 Barycentric Coordinates |
|
|
119 | (28) |
|
7.1 Definitions and First Theorems |
|
|
119 | (3) |
|
7.2 Centers of the Triangle |
|
|
122 | (1) |
|
7.3 Collinearity, Concurrence, and Points at Infinity |
|
|
123 | (3) |
|
|
|
126 | (3) |
|
7.5 A Demonstration from the IMO Shortlist |
|
|
129 | (3) |
|
|
|
132 | (1) |
|
7.7 Displacement Vectors, Continued |
|
|
133 | (2) |
|
|
|
135 | (7) |
|
7.9 When (Not) to Use Barycentric Coordinates |
|
|
142 | (1) |
|
|
|
143 | (4) |
|
|
|
147 | (66) |
|
|
|
149 | (20) |
|
|
|
149 | (2) |
|
|
|
151 | (3) |
|
8.3 An Example from the USAMO |
|
|
154 | (2) |
|
8.4 Overlays and Orthogonal Circles |
|
|
156 | (3) |
|
|
|
159 | (1) |
|
8.6 The Inversion Distance Formula |
|
|
160 | (1) |
|
8.7 More Example Problems |
|
|
160 | (5) |
|
|
|
165 | (1) |
|
|
|
165 | (4) |
|
|
|
169 | (26) |
|
|
|
169 | (1) |
|
|
|
170 | (3) |
|
|
|
173 | (3) |
|
|
|
176 | (2) |
|
9.5 Poles/Polars and Brocard's Theorem |
|
|
178 | (3) |
|
|
|
181 | (2) |
|
9.7 Projective Transformations |
|
|
183 | (2) |
|
|
|
185 | (5) |
|
|
|
190 | (5) |
|
10 Complete Quadrilaterals |
|
|
195 | (14) |
|
|
|
196 | (2) |
|
|
|
198 | (1) |
|
10.3 The Gauss-Bodenmiller Theorem |
|
|
198 | (2) |
|
10.4 More Properties of General Miquel Points |
|
|
200 | (1) |
|
10.5 Miquel Points of Cyclic Quadrilaterals |
|
|
201 | (1) |
|
|
|
202 | (3) |
|
|
|
205 | (4) |
|
|
|
209 | (4) |
|
|
|
213 | (2) |
|
Appendix A An Ounce of Linear Algebra |
|
|
215 | (6) |
|
A.1 Matrices and Determinants |
|
|
215 | (2) |
|
|
|
217 | (1) |
|
A.3 Vectors and the Dot Product |
|
|
217 | (4) |
|
|
|
221 | (20) |
|
Appendix C Selected Solutions |
|
|
241 | (62) |
|
C.1 Solutions to Chapters 1--4 |
|
|
241 | (10) |
|
C.2 Solutions to Chapters 5--7 |
|
|
251 | (21) |
|
C.3 Solutions to Chapters 8--10 |
|
|
272 | (11) |
|
C.4 Solutions to Chapter 11 |
|
|
283 | (20) |
|
Appendix D List of Contests and Abbreviations |
|
|
303 | (2) |
| Bibliography |
|
305 | (2) |
| Index |
|
307 | (4) |
| About the Author |
|
311 | |