Homework for Math 445 - Spring 2013


The homework assignment will be posted through the week and announced on the discussion board.  The homework assigned Monday through Friday on any given week is due the following Wednesday before lecture.
[AG] refers to the textbook “Axiomatic Geometry”.

Homework 1

due Wednesday, April 10

Reading: chapter 6, chapter 7

Writing: 6A, 6B, 7A, 7B, 7C

Homework 2

due Wednesday, April 17

Reading: Chapter 7

Writing: 7D, 7F, 7H

Problem 1. Let A, B be two points on one side of a line l. Construct a point P on the line l such that the quantity |AP| + |PB| is minimal, and prove that such point is unique.

Problem 2. Answer the following question with convincing justification: Which one of the Postulates 1-9 of Neutral geometry is inconsistent with the Elliptic parallel Postulate.

Bonus (worth 2 points): reformulate problem 1 so that it can be given to smart 6th graders, (assume they have some knowledge of geometry); that is, put a fun story problem behind the “dry” geometric formulation.

 

Special assignment, do by 11:59pm Wednesday, April 17

Make a discussion board post in the thread on E.O.Wilson’s Op-Ed in the WSJ

Homework 3

due Wednesday, April 24

Reading and writing: Carefully read the proof of Th. 7.23 in the book and then put it in your notes in your own words.

Reading: Chapter 9

Writing: 9B, 9C, 9D, 9E, 9G

Homework 4

due Wednesday, May 1

Reading: Ch. 10

Writing: 10A, 10B, 10C, 10E, 10F, 10G

Homework 5

due Wednesday, May 8

Reading: Ch. 10

Start working on your group projects

No written homework

Homework 6

due Wednesday, May 15

Reading: Ch. 11

Writing: 10M, 11A, 11D, 11G, Problem 5

Bonus: 11H

Homework 7

due Wednesday, May 22

Special homework (by Wednesday, 5/15): try to come up with your own proof of 12.9

Reading: chapter 12

Writing: 12A, 12D,

Problem 3: Let ΔABC be a triangle, let B’ be a point on the interior of the side AC and let D be a point on the interior of the cevian BB’.  Prove that S(ΔABD)/S(ΔCBD)=AB’/CB’.

12H (Hint: Use Problem 3 for the “if” direction; the “only if” direction is proved by contradiction).

Problem 5: Prove that the three angle bisectors of a triangle are concurrent.

Homework 8

Due Wednesday, May 29

Reading: Finish chapter 12.

Chapter 13 (most of the chapter, including the trigonometry section, is an independent study – we will not cover this material in class but you’ll be responsible for learning it for the final and homework)

Reading and Writing: write down theorems 12.16-12.20 in your notes and sketch the proofs (12.17 is a homework problem)

Writing: Homework 8

An interactive page where you experiment with different locations of the circumcenter: http://www.mathopenref.com/trianglecircumcenter.html

Homework 9

Due Wednesday, June 5

Reading: Chapter 16, up to “Constructible Points etc.” (pp.295-308)

Writing: Homework 9

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