This schedule will be regularly updated. It is your responsibility to check it accordingly.
Homework is due every Wednesday. Underlined problems in should be handed in.
When  Topics  #  Homework, Exams, Remarks. 
829  General
Information. Here are the first pages of the book. Discussion about axiom systems. History of geometry 1B Congruent Triangles 1C Angles and parallel lines 1D Parallelograms 
0  Homework 0: Fill this
form and play Euclid
the game, and/or , Euclidea
(you can also download it in a smart phone or tablet). 
95  1E Area 
1  Sept 5th, No class  Labor Day HW1: 1B  1,3, 4 1D  1, 3, 4, 5,12, 13,14 
912  1F Circles and arcs 1H Similarity 
2  In this
link you'll find corrections to known errors in the book. HW2: 1E: 1, 2, 3, 4 (In IE.3 add hypothesis the triangle is isosceles) Read and understand the proof of Problem 1.14 
919  2A The circumcircle 2B The centroid 2C The Euler line, Orthocenter, and NinePoint circle 
3  HW3: 1F: 2, 3, 5, 6, 7, 10, 11, 12,14. In the problem 1.F11, you need to produce a graph of the problem in Geogebra and share it with me (you will need to create a Geogebra account for that) . Think of this graph as a prop you would use to explain a student the problem. From Wednesday Sept 21st (including Sept 21st) the class will be held in 4130 Math Tower. 1H: 2, 3, 5, 8, 10. 
926  2C The Euler line, Orthocenter, and NinePoint circle (cont.) 2D Computations 2E The incircle 
4  By popular demand! Here
is "our" song: That's mathematics, and here
is his author, Tom Lehrer, signing, and here
are the lyrics. HW4: 1H: 5, 10. 2A: 1, 5 2B: 1, 2, 4 2C: 1, 2. 
103  Curvature 
5  2C: 4, 6. 2D: 1, 2 2E: 1, 3, 4, 5 In Geogebra, create a triangle and label all its "special" points (centroid, feet of altitudes, midpoints of sides, etc. They are 12: 9 in the nine point circle and three in the Euler line). Verify the Nine Point Circle Theorem and the Euler Line Theorem. Mark and label the center of the Nine Point Circle. Verify the relations between the (pairwise) distances between orthocenter, circumcenter and centroid. Share the file with me in Geogebra. First Midterm: Chapters 1 (except Section 1G) and Chapter 2 (Except Sections 2F, 2G and 2H) Here is a nice page about different geometries, including the bear problem. (The whole website is quite interesting) 
1010  G Morley's theorem 2F Exscribed circles 2H Optimization in triangles 
6  In Geogebra, create a triangle, and find its incircles
and the three excircles (Figure 2.21 of the textbook). Of
course, the only "free" objects of the graph must be the
three vertices. Verify Theorem 2.34 of the textbook by computing
the sum of the inverses of the radius of the excircles minus the
inverse of the radius of the incircle. In Geogebra, create a triangle and construct the three angle trisectors. Highlight Morley's triangle and verify it is equilateral. Share both files with me. Also, the problem 5 for the midterm : Prove that the ninepoint circle bisects any segment connecting the orthocenter to a point on the circumcircle. (Hint: Recall that the radius of the ninepoint circle is half the radius of the circumcircle) 
1017  Spherical geometry. 
7  2F: 1, 2. 2G: 1. 2H: 1. Submit the three underlined problems above and problems A and B below. A. Determine what is the figure formed by the intersections of the four pairs of adjacent angle quadrisectors of the angles of a square (As in Morley theorem, consider each intersection of two angle quadrisectors which are closer to a side). Prove your findings. B . Read the proof of Morley's theorem in the textboox and write up a version of that proof in your own words. Extra credit: Find a formula for the length of the sides of the equilateral triangle determined by the angle trisectors of a triangle. Your formula should be in terms of the angles of the triangle and the circumradius. Also, the problem 5 for the midterm (if you did not do it yet): Prove that the ninepoint circle bisects any segment connecting the orthocenter to a point on the circumcircle. (Hint: Recall that the radius of the ninepoint circle is half the radius of the circumcircle) Morley Theorem https://ggbm.at/cRKQqhSe 
1024  Isometries. Here and here you'll find good introductions to isometries and here are notes by Oleg Viro, revised by Olga Plamevskaya. Geogebra Isometries case 1 Isometries case 2 In class, we will work with this handout. 
8  This homework contains a bit of review of previous topics. 1. In class we discussed under which hypothesis the SSA criteria for congruence of triangles holds. In this problem, you are asked to list all possible cases as we did in class, and prove why in each of these cases the SSA criteria hold or does not hold. 2. Use the spherical law of cosines to calculate the greatcircle distance NY (40.7^{o}N,74^{o}W) to Tashkent (41.3^{o}N, 69.2^{o}E). 3. Prove that if two sides of a triangle are unequal, then the larger side has a larger angle opposite to it. 4. . Prove that if two angles of a triangle are unequal, then the larger angle has a larger side opposite to it. 5. In triangle ABC, A line AD is drawn, where D is a point in BC. From B and C two perpendiculars to line AD are dropped, intersecting AD in E and F. If M is the midpoint of BC, prove that FME is isosceles. 6. In any quadrilateral, the lines joining the midpoints of each pair of opposite sides and the line joining the midpoints of the diagonals are concurrent. 
1031  Isometries. 
9  Problems for this week are here.
Hand in problems 2, 5,11, 12, 13, 14 (In problem 14, you only need
to produce an appropriate list of symmetries, no need of proofs in
this problem); 
117  Similarities. Notes
by notes by Oleg Viro, revised by Olga Plamevskaya Interesting Geogebra resources for geometry. Stretch rotation example Stretch reflection example 
10 
Problems for this week are here. 
1114  6A Rules of the game 6B Reconstructing triangles 
11  Second midterm (focused on Sections 2F, 2G, 2H, Isometries. ) Homework for this week is here. Please hand in these problems on Monday Nov 21st. Remember to make two sets, one containing problems 1 to 5, the other containing problems 67 and, if you want problem 1 from HW 10. 
1121  6C Tangents 
No homework this week. 1123 No class Thanksgiving Break 

1128  6D Three hard problems 6E Constructible numbers 6F Changing the rules 
12  6A 1, 2, 3, 4, 5, 6. 6B 1, 2, 3, 4. ( (hint for 1 and 3: when is an inscribed angle on a circle is right?) 
125  Extra topics and review We will work with this handout from the book "Project Origami" by Thomas Bull 

Final Exam: Thursday, Dec. 15, 8:30pm11:00pm  